maintainers: add cirno-999

maintainers/maintainer-list.nix

···
     githubId = 3956062;
     name = "Simon Lackerbauer";
   };
+  cirno-999 = {
+    email = "[e-mail]";
+    github = "cirno-999";
+    githubId = 73712874;
+    name = "cirno-999";
+  };
   citadelcore = {
     email = "[e-mail]";
     github = "citadelcore";