remove unused source/patch files from git
    
    Remove the following files which are no longer used:
    
      - dnf-rpm.conf: unused since d27cad7 (Upgrade to 7.5.5, 2021-01-26)
      - cron.patch: unused since 301b36f (Upgrade to new upstream release,
        2021-07-24) [7.5.6-1]
      - systemd-user.patch: unused since a09b9c4 (Upgraded to new upstream
        release, 2022-01-23) [7.6-1]