add myself to the maintainers list

This is my second patch to the tlaplus package and I agreed to add
myself as a maintainer on my next contribution.

maintainers/maintainer-list.nix

@@ -10145,6 +10145,11 @@
     githubId = 9469313;
     name = "Gregoire Martinache";
   };
+  mgregson = {
+    github = "mgregson";
+    githubId = 333572;
+    name = "Michael Gregson";
+  };
   mgttlinger = {
     email = "megoettlinger@gmail.com";
     github = "mgttlinger";

pkgs/applications/science/logic/tlaplus/default.nix

@@ -32,6 +32,6 @@ stdenv.mkDerivation rec {
     sourceProvenance = with lib.sourceTypes; [ binaryBytecode ];
     license     = lib.licenses.mit;
     platforms   = lib.platforms.unix;
-    maintainers = with lib.maintainers; [ florentc thoughtpolice ];
+    maintainers = with lib.maintainers; [ florentc thoughtpolice mgregson ];
   };
 }