metamorphose2: migrate to wxPython_4_2

pkgs/applications/misc/metamorphose2/default.nix

···
   '';
 
   nativeBuildInputs = [ makeWrapper ];
-  propagatedBuildInputs = with python3.pkgs; [ mutagen wxPython_4_1 pillow six ];
+  propagatedBuildInputs = with python3.pkgs; [ mutagen wxPython_4_2 pillow six ];
 
   makeFlags = [ "PREFIX=$(out)" ];