cosmic-player: wrap with GST_PLUGIN_SYSTEM_PATH_1_0

gst_all_1.gstreamer populates GST_PLUGIN_SYSTEM_PATH_1_0, but
it is not automatically wrapped with the binary of the package

pkgs/by-name/co/cosmic-player/package.nix

@@ -66,6 +66,10 @@ rustPlatform.buildRustPackage rec {
     "target/${stdenv.hostPlatform.rust.cargoShortTarget}/release/cosmic-player"
   ];
 
+  postInstall = ''
+    libcosmicAppWrapperArgs+=(--prefix GST_PLUGIN_SYSTEM_PATH_1_0 : "$GST_PLUGIN_SYSTEM_PATH_1_0")
+  '';
+
   meta = {
     homepage = "https://github.com/pop-os/cosmic-player";
     description = "Media player for the COSMIC Desktop Environment";