mopidy: use setuptools_80 at runtime

Mopidy 3.4.2 and its extensions still import pkg_resources, which was removed from setuptools 82. Keep the current build system while retaining the runtime API with setuptools_80.

Assisted-by: pi coding agent / Mika (OpenAI gpt-5.6-sol)

pkgs/applications/audio/mopidy/mopidy.nix

@@ -51,7 +51,9 @@ pythonPackages.buildPythonApplication (finalAttrs: {
       pygobject3
       pykka
       requests
-      setuptools
+      # Provides pkg_resources required by Mopidy 3 and affected extensions.
+      # Remove when updating to Mopidy 4.
+      setuptools_80
       tornado
     ]
     ++ lib.optionals (!stdenv.hostPlatform.isDarwin) [ dbus-python ];