maintainers: add p-h

maintainers/maintainer-list.nix

···
     githubId = 3438604;
     name = "Petter Storvik";
   };
+  p-h = {
+    email = "[e-mail]";
+    github = "p-h";
+    githubId = 645664;
+    name = "Philippe Hürlimann";
+  };
   philandstuff = {
     email = "[e-mail]";
     github = "philandstuff";