maintainer: add nomis

maintainers/maintainer-list.nix

···
     githubId = 148037;
     name = "Joachim Breitner";
   };
+  nomis = {
+    email = "[e-mail]";
+    github = "nomis";
+    githubId = 70171;
+    name = "Simon Arlott";
+  };
   nomisiv = {
     email = "[e-mail]";
     github = "NomisIV";