gnome.gnome-control-center: fix crash in Mouse panel

The Mouse panel uses GtkPicture to display VP9-encoded webm clips.
Without GStreamer, the panel would crash with:

    ERROR: GstPlay: 'playbin' element not found, please check your setup

Fixes: https://github.com/NixOS/nixpkgs/issues/253928

pkgs/desktops/gnome/core/gnome-control-center/default.nix

@@ -23,6 +23,7 @@
 , gnome
 , gsettings-desktop-schemas
 , gsound
+, gst_all_1
 , gtk4
 , ibus
 , libgnomekbd
@@ -134,7 +135,11 @@ stdenv.mkDerivation rec {
     tracker-miners # for search locations dialog
     udisks2
     upower
-  ];
+  ] ++ (with gst_all_1; [
+    # For animations in Mouse panel.
+    gst-plugins-base
+    gst-plugins-good
+  ]);
 
   preConfigure = ''
     # For ITS rules