fix: fetch correct type in pydantic

[phi-friday]

related: #206, #207, python/cpython#113702

sample code:

from __future__ import annotations

from pprint import pprint
from typing import Annotated, Any, TypeAlias, get_type_hints

from pydantic import BaseModel
from pydantic.annotated_handlers import GetCoreSchemaHandler
from pydantic_core import core_schema

import expression as ex


T: TypeAlias = "Annotated[str, 1]"
T2: TypeAlias = Annotated[str, 1]


class Username(str):
    @classmethod
    def __get_pydantic_core_schema__(cls, source_type: Any, handler: GetCoreSchemaHandler) -> Any:
        # https://github.com/dbrattli/Expression/issues/206
        return core_schema.no_info_after_validator_function(cls, handler(str))


class Sample(BaseModel):
    a: T = "foo"
    b: T2 = "bar"
    c: str | None = None
    d: Annotated[Annotated[Annotated[T, 1], 2], 3] = "baz"
    e: Username = Username("spam")
    f: Annotated[Annotated[Username, 1], 2] = Username("eggs")
    options_a: ex.Option[Username] = ex.option.Nothing
    options_b: ex.Option[Annotated[Annotated[Username, 1], 2]]
    options_c: ex.Option[Annotated[Annotated[Username, 1], 2]]
    result_a: ex.Result[Username, Any]
    result_b: ex.Result[Annotated[Annotated[Username, 1], 2], Any]
    result_c: ex.Result[Annotated[Annotated[Username, 1], 2], Any]


hints = get_type_hints(Sample)
pprint(hints)
schema = Sample.model_json_schema()
pprint(schema)

before:

❯ poetry run python sample.py
Traceback (most recent call last):
  File "/Users/***/git/python/private/Expression/sample.py", line 24, in <module>
    class Sample(BaseModel):
  File "/Users/***/git/python/private/Expression/.venv/lib/python3.10/site-packages/pydantic/_internal/_model_construction.py", line 205, in __new__
    complete_model_class(
  File "/Users/***/git/python/private/Expression/.venv/lib/python3.10/site-packages/pydantic/_internal/_model_construction.py", line 552, in complete_model_class
    cls.__pydantic_validator__ = create_schema_validator(
  File "/Users/***/git/python/private/Expression/.venv/lib/python3.10/site-packages/pydantic/plugin/_schema_validator.py", line 50, in create_schema_validator
    return SchemaValidator(schema, config)
pydantic_core._pydantic_core.SchemaError: Error building "model" validator:
  SchemaError: Error building "model-fields" validator:
  SchemaError: Field "options_b":
  SchemaError: Error building "json-or-python" validator:
  SchemaError: Error building "chain" validator:
  SchemaError: Error building "function-before" validator:
  SchemaError: Error building "union" validator:
  SchemaError: Error building "chain" validator:
  SchemaError: Error building "is-instance" validator:
  SchemaError: 'cls' must be valid as the first argument to 'isinstance'

after:

❯ poetry run python sample.py
{'a': <class 'str'>,
 'b': <class 'str'>,
 'c': str | None,
 'd': <class 'str'>,
 'e': <class '__main__.Username'>,
 'f': <class '__main__.Username'>,
 'options_a': expression.core.option.Option[__main__.Username],
 'options_b': expression.core.option.Option[__main__.Username],
 'options_c': expression.core.option.Option[__main__.Username],
 'result_a': expression.core.result.Result[__main__.Username, typing.Any],
 'result_b': expression.core.result.Result[__main__.Username, typing.Any],
 'result_c': expression.core.result.Result[__main__.Username, typing.Any]}
{'properties': {'a': {'default': 'foo', 'title': 'A', 'type': 'string'},
                'b': {'default': 'bar', 'title': 'B', 'type': 'string'},
                'c': {'anyOf': [{'type': 'string'}, {'type': 'null'}],
                      'default': None,
                      'title': 'C'},
                'd': {'default': 'baz', 'title': 'D', 'type': 'string'},
                'e': {'default': 'spam', 'title': 'E', 'type': 'string'},
                'f': {'default': 'eggs', 'title': 'F', 'type': 'string'},
                'options_a': {'default': {'none': None, 'tag': 'none'},
                              'title': 'Options A'},
                'options_b': {'title': 'Options B'},
                'options_c': {'title': 'Options C'},
                'result_a': {'anyOf': [{'properties': {'ok': {'title': 'Ok',
                                                              'type': 'string'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'ok'],
                                        'type': 'object'},
                                       {'properties': {'error': {'title': 'Error'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'error'],
                                        'type': 'object'}],
                             'title': 'Result A'},
                'result_b': {'anyOf': [{'properties': {'ok': {'title': 'Ok',
                                                              'type': 'string'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'ok'],
                                        'type': 'object'},
                                       {'properties': {'error': {'title': 'Error'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'error'],
                                        'type': 'object'}],
                             'title': 'Result B'},
                'result_c': {'anyOf': [{'properties': {'ok': {'title': 'Ok',
                                                              'type': 'string'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'ok'],
                                        'type': 'object'},
                                       {'properties': {'error': {'title': 'Error'},
                                                       'tag': {'title': 'Tag',
                                                               'type': 'string'}},
                                        'required': ['tag', 'error'],
                                        'type': 'object'}],
                             'title': 'Result C'}},
 'required': ['options_b', 'options_c', 'result_a', 'result_b', 'result_c'],
 'title': 'Sample',
 'type': 'object'}