nixos/tests/bazarr: fix eval error

The test still doesn't pass, it has some runtime issues as well.

Fixes: 5803706662 ("nixos/tests: fix type mismatch in wait_for_open_port")

nixos/tests/bazarr.nix

@@ -16,11 +16,12 @@ in
         enable = true;
         listenPort = port;
       };
+      nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) ["unrar"];
     };
 
   testScript = ''
     machine.wait_for_unit("bazarr.service")
-    machine.wait_for_open_port(port)
+    machine.wait_for_open_port(${toString port})
     machine.succeed("curl --fail http://localhost:${toString port}/")
   '';
 })