Add Alpine 3.20

[skyeforeverblue]

Adds metadata for Alpine Linux 3.20

[skyeforeverblue]

(I can add myself as a maintainer in the Containerfile, but I didn't really do much of anything beside bump the version string.)

[castrojo]

Thanks for this, adding the CI bits. As you can see it's not that hard to keep up to date, all I do is update the version string. If you're keen to co-maintain we can do it together!

[skyeforeverblue]

Thanks for this, adding the CI bits. As you can see it's not that hard to keep up to date, all I do is update the version string. If you're keen to co-maintain we can do it together!

Sounds good to me, I have no problems with just updating a couple strings every once in a while. Plus, being on Silverblue means I can (hopefully) spin up test containers quickly if the need arises.