Alpine 3.18.12, 3.19.7, 3.20.6 and 3.21.3 released

The new releases have security fixes for OpenSSL and musl

See: https://www.alpinelinux.org/posts/Alpine-3.18.12-3.19.7-3.20.6-3.21.3-released.html

It's a bit unfortunate to serve the old download links.

I tried to create a MR for this, and could update the data/os/alpinelinux.org/alpinelinux-3.21.xml.in file, but couldn't figure out how to update the data in tests. It's not mentioned in CONTRIBUTING.md how these test files should be added.

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