maintainers: add maxhille

maintainers/maintainer-list.nix

···
     githubId = 35892750;
     name = "Maxine Aubrey";
   };
+  maxhille = {
+    email = "[e-mail]";
+    github = "maxhille";
+    githubId = 693447;
+    name = "Max Hille";
+  };
   maxhbr = {
     email = "[e-mail]";
     github = "maxhbr";