chore: remove use of now-invalid override from pyqt6

overrides/default.nix

@@ -2790,11 +2790,7 @@ lib.composeManyExtensions [
 
       pyqt6 =
         let
-          # The build from source fails unless the pyqt6 version agrees
-          # with the version of qt6 from nixpkgs. Thus, we prefer using
-          # the wheel here.
-          pyqt6-wheel = prev.pyqt6.override { preferWheel = true; };
-          pyqt6 = pyqt6-wheel.overridePythonAttrs (old:
+          pyqt6 = prev.pyqt6.overridePythonAttrs (old:
             let
               confirm-license = pkgs.writeText "confirm-license.patch" ''
                 diff --git a/project.py b/project.py