tests/hurl: disable for now

Will be re-enabled after NixOS/nixpkgs#418842
reaches unstable.

Author: khaneliman

tests/test-sources/plugins/by-name/hurl/default.nix

@@ -1,4 +1,6 @@
-{
+{ pkgs, ... }:
+# TODO: remove once https://github.com/NixOS/nixpkgs/pull/418842 hits flake.lock
+pkgs.lib.optionalAttrs false {
   empty = {
     plugins.hurl.enable = true;
   };