Set up GitHub Actions CI workflow for automated testing on PRs

[coderabbitai]

Overview

As discussed in PR #44, we need to set up a GitHub Actions workflow to automatically run all tests on each Pull Request.

Specifications

The workflow should:

• Trigger on each PR and push to main branch
• Run the following commands from the Makefile:
  • black for code formatting check
  • flake8 for linting
  • pylint for static code analysis
  • ruff for additional linting/checking
  • pytest for running all tests
• Fail the check if any of these commands fail
• Show test results in the PR

Additional considerations

• Consider caching dependencies to speed up workflow
• Consider using separate jobs for linting vs testing
• Ensure it works with the new source directory structure (src instead of lib)

Reference

• Originally requested by @Gui-FernandesBR in PR API V3 Refactoring #44
• URL: API V3 Refactoring #44 (comment)