systemd: fix 0019-*.patch

This was introduced in https://github.com/NixOS/nixpkgs/pull/99621, but
didn't follow the process documented in
pkgs/os-specific/linux/systemd/default.nix, namely, the `git am` and
`git format-patch` workflow, which caused
`0019-revert-get-rid-of-seat_can_multi_session.patch` to not apply with
`git am` due to missing authorship information.

I did apply this patch manually, and copied authorship information from
4e384ddc11.

pkgs/os-specific/linux/systemd/default.nix

@@ -88,7 +88,7 @@ in stdenv.mkDerivation {
     ./0016-systemd-sleep-execute-scripts-in-etc-systemd-system-.patch
     ./0017-kmod-static-nodes.service-Update-ConditionFileNotEmp.patch
     ./0018-path-util.h-add-placeholder-for-DEFAULT_PATH_NORMAL.patch
-    ./0019-revert-get-rid-of-seat_can_multi_session.patch
+    ./0019-logind-seat-debus-show-CanMultiSession-again.patch
   ];
 
   postPatch = ''