Create python-app.yml

[rajabit111]

[ageron]

Hi @rajabit111 ,

Thanks for the PR, however I've tried something like this before and unfortunately it failed because the notebooks run for too long, so GitHub interrupts them with an error. Moreover, I don't currently have any pytests, so I would have to implement add some, and I think I'd prefer just running the notebooks. There might be a simple way to get GitHub to accept running for a long time, but I'm not aware of it.