Remove recipe for git-commit and packages depending on it

Since [1: 301c815] git-commit was only a stub.

Three packages packages remained that still depended on git-commit.

- The maintainer of git-commit+ was asked to drop the dependency
  in nonsequitur/git-gutter-plus#48.
  This has not happened yet and it appears the package has to be
  considered unmaintained.  It was a fork of git-gutter.  See
  also nonsequitur/git-gutter-plus#36.

- git-gutter-fringe+ depends on git-gutter+.

- The maintainer of magithub deprecated it a long time ago, in
  favor of forge.

Remove these three packages as well.

1: 2024-09-01 301c815
   Inform users that they have to uninstall git-commit

Author: tarsius