python.buildEnv: always include the $out output

28299f669a introduced the first Python
packages having multiple outputs. The required outputs were not picked
up by `python.buildEnv` (#31857).

This commit modifies `python.buildEnv` so that it always includes the
$out output and thus fixes #31857.

pkgs/development/interpreters/python/wrapper.nix

@@ -14,7 +14,8 @@ let
     name = "${python.name}-env";
 
     inherit paths;
-    inherit ignoreCollisions extraOutputsToInstall;
+    inherit ignoreCollisions;
+    extraOutputsToInstall = [ "out" ] ++ extraOutputsToInstall;
 
     postBuild = ''
       . "${makeWrapper}/nix-support/setup-hook"