Provide bindists with old glibc compatibility

Switching to Fedora 33 has caused a lot of issues: https://github.com/haskell/haskell-language-server/issues/3247

GHCup uses fedora bindists for "unknown" distros. But 33's glibc is too new.

Debian (e.g. version 9) is a bad choice as a default, because it has low cross distro compatibility, e.g. https://bugzilla.redhat.com/show_bug.cgi?id=1875587

I've tried the centos 7 one, which seems to work much better, but centos (as a whole) seems to be EOL as of 2024. There are alternative RHEL based distros that could fill the gap, such as https://de.wikipedia.org/wiki/AlmaLinux or https://de.wikipedia.org/wiki/Rocky_Linux

Alternatively, we could continue to provide an ancient fedora 27 bindist, although it's already past EOL.