maintainers: add ik-nz (#403849)

maintainers/maintainer-list.nix

···
     githubId = 7481521;
     name = "Balázs Lengyel";
   };
+  ik-nz = {
+    email = "[e-mail]";
+    github = "ik-nz";
+    githubId = 207392575;
+    name = "Isaac Kabel";
+  };
   ilarvne = {
     email = "[e-mail]";
     github = "ilarvne";