Add Alpine Linux 3.20, drop 3.16

[frenck]

SSIA

Add Alpine Linux 3.20: https://alpinelinux.org/posts/Alpine-3.20.0-released.html

This means the oldest drops from our support, which is Alpine 3.16

[bdraco]

not sure it matters for us by yq got renamed https://gitlab.alpinelinux.org/alpine/aports/-/issues/16052

[frenck]

not sure it matters for us by yq got renamed

Yeah, I'm aware. It isn't used in our base images. From the community add-ons repositories, I was affected (and adjusted). Nevertheless yq is now pointing at yq-go using a meta package, so even if it would be the case, it will still work as normal.

../Frenck