Remove redundant syntax

[chihchenghuang]

little things.
I noticed you used virtual package in the alpine dockerfile.
As I know, once you use this feature, you don't have to list all packages in the apk del command.
apk del .build-deps should work perfect here.

https://github.com/tiangolo/uvicorn-gunicorn-docker/blob/master/docker-images/python3.7-alpine3.8.dockerfile#L7

more discussions:
https://stackoverflow.com/questions/46221063/what-is-build-deps-for-apk-add-virtual-command/46222036

Inpired a lot by your repo. good job man!

[tiangolo]

Thank you! And sorry for the very long delay. 😅

At some point I deprecated Alpine. 😅 And now that Uvicorn supports managing workers with --workers, including restarting dead ones, there's no need for Gunicorn. That also means that it's much simpler to build a Docker image from scratch now, I updated the docs to explain it.

Because of that, I deprecated this Docker image: https://github.com/tiangolo/uvicorn-gunicorn-docker#-warning-you-probably-dont-need-this-docker-image