Motivation for this change

The github repo doesn't seem to be updated any longer.

I was also condering renaming the package to lowercase abcmidi because most distros do so:
https://repology.org/metapackage/abcmidi/versions
The only problem I see is that it wouldn't be updated if already installed, if I am correct.
What do you think?

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

ping @rycee