{gpauth,gpclient}: Add m1dugh as a maintainer

@m1dugh has contributed a lot in #350777. The upstream state of the GUI
component combined with the paid licensing model has made it daunting to
consider integrating into nixpkgs. Instead, add @m1dugh as a co-maintainer
for the existing v2 packages.

Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>

pkgs/by-name/gp/gpauth/package.nix

@@ -45,6 +45,9 @@ rustPlatform.buildRustPackage rec {
     '';
     homepage = "https://github.com/${src.owner}/${src.repo}";
     license = with licenses; [ gpl3Only ];
-    maintainers = with maintainers; [ binary-eater ];
+    maintainers = with maintainers; [
+      binary-eater
+      m1dugh
+    ];
   };
 }