Remove usage of pyup

They require to sign up to a paid plan to use the service now.

README.md

@@ -8,8 +8,6 @@ a query language for APIs created by Facebook.
 [![Documentation Status](https://readthedocs.org/projects/graphql-core-3/badge/)](https://graphql-core-3.readthedocs.io)
 ![Test Status](https://github.com/graphql-python/graphql-core/actions/workflows/test.yml/badge.svg)
 ![Lint Status](https://github.com/graphql-python/graphql-core/actions/workflows/lint.yml/badge.svg)
-[![Dependency Updates](https://pyup.io/repos/github/graphql-python/graphql-core/shield.svg)](https://pyup.io/repos/github/graphql-python/graphql-core/)
-[![Python 3 Status](https://pyup.io/repos/github/graphql-python/graphql-core/python-3-shield.svg)](https://pyup.io/repos/github/graphql-python/graphql-core/)
 [![Code Style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 The current version 3.2.1 of GraphQL-core is up-to-date with GraphQL.js version 16.3.0.

setup.cfg

@@ -4,10 +4,6 @@ python-tag = py3
 [aliases]
 test = pytest
 
-[check-manifest]
-ignore =
-  .pyup.yml
-
 [tool:pytest]
 # Only run benchmarks as tests.
 # To actually run the benchmarks, use --benchmark-enable on the command line.