treewide: remove unused with statements from maintainer lists

$ find -type f -name '*.nix' -print0 | xargs -P "$(nproc)" -0 sed -i \
  -e 's!with lib.maintainers; \[ *\];![ ];!' \
  -e 's!with maintainers; \[ *\];![ ];!'

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

@@ -57,7 +57,7 @@ buildPythonPackage rec {
     homepage = "https://bitbucket.org/zzzeek/alembic";
     description = "Database migration tool for SQLAlchemy";
     license = licenses.mit;
-    maintainers = with maintainers; [ ];
+    maintainers = [ ];
     mainProgram = "alembic";
   };
 }