Restored reference to GCP gym registry. (#6108)

Author: miguelalonsojr

ml-agents-envs/mlagents_envs/registry/unity_env_registry.py

@@ -121,6 +121,6 @@ def __iter__(self) -> Iterator[Any]:
 
 default_registry = UnityEnvRegistry()
 # TODO restore when a new registry is available.
-# default_registry.register_from_yaml(
-#     "https://storage.googleapis.com/mlagents-test-environments/1.1.0/manifest.yaml"
-# )  # noqa E501
+default_registry.register_from_yaml(
+    "https://storage.googleapis.com/mlagents-test-environments/1.1.0/manifest.yaml"
+)  # noqa E501