maintainers: add mbprtpmnr

maintainers/maintainer-list.nix

···
     github = "rski";
     githubId = 2960312;
   };
+  mbprtpmnr = {
+    name = "mbprtpmnr";
+    email = "[e-mail]";
+    github = "mbprtpmnr";
+    githubId = 88109321;
+  };
+
 }