Use 'pip --no-cache' and remove '*.pyc' files after installation

[pmav99]

With the proposed patch the size of the images get reduced by ~15MB each, which for the alpine-based images translates into more than 10% of the total size.

If you want I can make a Pull Request for uvicorn-gunicorn-fastapi-docker, too

[tiangolo]

Thanks! I see the documented option is --no-cache-dir, so I updated it to use that.

I'm not sure about removing *.pyc files, so let's leave it as the simplest change for now.

Thanks for your contribution! 🚀 🍰

[pmav99]

just for the record, what is your concern about the *.pyc files?

[tiangolo]

That they are created either way while running, so adding extra logic to do something that might not actually do much would end up adding extra complexity without a very clear benefit.