maintainers: add ettom

maintainers/maintainer-list.nix

···
     githubId = 32169529;
     name = "Etienne Jean";
   };
+  ettom = {
+    email = "[e-mail]";
+    github = "ettom";
+    githubId = 36895504;
+    name = "ettom";
+  };
   etu = {
     email = "[e-mail]";
     matrix = "@etu:semi.social";