Merge pull request #290001 from a-kenji/fix/cosmic-session

cosmic-session: fix xdg-desktop-portal-cosmic path

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

···
     "--set"
     "prefix"
     (placeholder "out")
-    "--set"
-    "xdp_cosmic"
-    xdg-desktop-portal-cosmic
   ];
+
+  env.XDP_COSMIC = lib.getExe xdg-desktop-portal-cosmic;
 
   passthru.providedSessions = [ "cosmic" ];