libinput: 1.2.1 -> 1.2.2, propagate udev dependency

[groxxda]

Things done:

• Tested using sandboxing (nix-build --option build-use-chroot true or nix.useChroot on NixOS)
• Built on platform(s)
  • NixOS
  • OS X
  • Linux
• 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.

[mention-bot]

By analyzing the blame information on this pull request, we identified @colemickens, @fpletz and @codyopel to be potential reviewers

[colemickens]

What exactly does it mean to move it from a build input to a propagatedbuild input? Just for my own learning/understanding? Thanks. (Looks good to me otherwise.)

[groxxda]

Propagating it makes udev available to packages that depend on libinput. Otherwise a package that depends on libinput will also need an explicit dependency to udev.