Use alpine images on Swoole and Docker

[dir]

This is a PR for issue #76, "add alpine images".

I have not altered the FrankenPHP.Dockerfile as I don't use FrankenPHP and am not sure which image to select or how to reliably test it.

The changes in this PR are pretty straightforward, and nearly identical on the RoadRunner and Swoole docker files.

Potential Issues:

• not sure if changing the #!/usr/bin/env sh line on top of start-container will effect the FrankenPHP image.
• haven't tested RoadRunner fully enough yet

As for next steps, assuming everything works well on you guys' end, I'm not sure if it would be best to:

• Replace the original files
• Create separate "alpine" branch/release
• Add additional files to this repo

[smortexa]

Thanks for your contribution! I think creating new Dockerfiles like Swoole.Alpine.Dockerfile instead of modifying our existing Debian-based Dockerfiles is a better idea. After that, we can think about moving Dockerfiles to a new directory and updating GitHub Actions.

[dir]

It's my pleasure! This repo has saved me hours of my life, it's the least I can do.

I'll go ahead and alter the PR to introduce those new files and keep the original ones untouched.

[dir]

@smortexa I have altered the PR to make the Alpine files separate!

The start-container is still the same with the alteration of Line 1
#!/usr/bin/env bash -> #!/usr/bin/env sh