maintainers: add dlip

maintainers/maintainer-list.nix

···
     githubId = 28980797;
     name = "David Leslie";
   };
+  dlip = {
+    email = "[e-mail]";
+    github = "dlip";
+    githubId = 283316;
+    name = "Dane Lipscombe";
+  };
   dmalikov = {
     email = "[e-mail]";
     github = "dmalikov";