nixos/tests/mongodb: remove non-existent maintainer

nixos/tests/mongodb.nix

···
   in {
     name = "mongodb";
     meta = with pkgs.lib.maintainers; {
-      maintainers = [ bluescreen303 offline cstrahan rvl phile314 ];
+      maintainers = [ bluescreen303 offline rvl phile314 ];
     };
 
     nodes = {