Add GitHub Actions CI/CD example for Flask app deployment

[davmano]

What This Adds

This PR introduces a new example under ci-cd/github-actions-flask-deploy:

• ✅ A simple Flask app (app.py)
• ✅ Requirements file
• ✅ GitHub Actions workflow (.github/workflows/flask-deploy.yml)
• ✅ Clean and professional README.md with badges
• ✅ Placeholder for deployment step with guidance for customization

Highlights

• Uses Python 3.10 via setup-python
• Includes install and (optional) test steps
• Ready for real-world extension (EC2, Heroku, etc.)
• Includes instructions and local setup guide

Why It Matters

This helps DevOps learners or engineers get started with GitHub Actions for CI/CD pipelines using a realistic, minimal Flask app — a common use case.

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Let me know if you'd like a second PR to demonstrate actual deployment to EC2 or Render.

[tungbq]

Thanks for your contribution @davmano, I appreciate your interested on this project. this PR looks good to me, just one comment about the auto trigger event.
This would trigger and run the pipeline every push on main even if it's not related to the github-actions-flask-deploy project. Can you please add the filter on this push to only run when there has any change in the github-actions-flask-deploy folder only. Thanks.

[tungbq]

Hi @davmano please also move this project content under projects (./projects/github-actions-flask-deploy https://github.com/tungbq/devops-project/tree/main/projects. Thanks