Add Type Hints as specified in is-charms-contributing-guide

[javierdelapuente]

Applicable spec:

Overview

Add the type hints that are specified in the is-charms-contributing-guide.

Variables chaos-* are also removed from the integration test yaml file, as those input variables were deleted from operator-workflows and the pipeline was failing.

Rationale

Juju Events Changes

Module Changes

Library Changes

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

[github-actions]

Test coverage for 6f2af57

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py      32      0      4      0   100%
----------------------------------------------------------
TOTAL             32      0      4      0   100%

Static code analysis report

Run started:2024-03-06 13:47:28.361838

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 151
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):