Proposal: Add GitHub Actions for CI (Testing)

[ariefshaik7]

Summary
The repository currently lacks CI workflows for continuous integration. I propose adding the following GitHub Actions workflows:

• Automated testing with pytest on all PRs/pushes.

Implementation

• Add .github/workflows/unit-tests.yml for pytest.

Next Steps:
I will draft the GitHub Actions workflows for testing with pytest similar to the adk-python repo and submit a pull request for review.