python3Packages.notobuilder: specify meta.license (#447202)

pkgs/development/python-modules/notobuilder/default.nix

···
   meta = {
     description = "Python module for building Noto fonts";
     homepage = "https://github.com/notofonts/notobuilder";
-    license = lib.licenses.unfree;
+    license = lib.licenses.asl20;
     maintainers = with lib.maintainers; [ jopejoe1 ];
   };
 }