Add Python 3.13 support

[Copilot]

This PR adds support for Python 3.13 to the readme-coverage-badger package.

Changes

The following configuration files have been updated to include Python 3.13:

• setup.cfg:

  • Added Programming Language :: Python :: 3.13 classifier
  • Added py313 to tox envlist
  • Updated [gh-actions] mapping to run lint and tests on Python 3.13

• .github/workflows/main.yml:

  • Added "3.13" to the Python version matrix for CI/CD testing across all platforms (Ubuntu, macOS, Windows)

• pyproject.toml:

  • Added 'py313' to black formatter target-version list

Testing

All existing tests pass on Python 3.12.3, and all linters (black, isort, flake8, mypy) pass successfully. No code changes were required as the package already works with Python 3.13 - only configuration updates were needed.

Related

This follows the same pattern as the previous Python 3.11 and 3.12 support addition in v1.0.0 (commit e30c803).

Original prompt

Create a pull request to add python 3.13 support. This mainly involves updating setup.cfg and .github/workflows/main.yml

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.95%. Comparing base (6ceeda0) to head (2b04631).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #147   +/-   ##
=======================================
  Coverage   80.95%   80.95%           
=======================================
  Files           2        2           
  Lines         126      126           
  Branches       10       10           
=======================================
  Hits          102      102           
  Misses         20       20           
  Partials        4        4           

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