nixosTests.isso: fix failing test

The test failed because the python variable port wasn't defined. We
insert the nix variable port with string interpolation instead.

kilianar 1339f1e0 cf63df03

Changed files
+1 -1
nixos
tests
+1 -1
nixos/tests/isso.nix
···
''
machine.wait_for_unit("isso.service")
-
machine.wait_for_open_port(port)
+
machine.wait_for_open_port(${toString port})
machine.succeed("curl --fail http://localhost:${toString port}/?uri")
machine.succeed("curl --fail http://localhost:${toString port}/js/embed.min.js")