fix numpy import error

rasa/plugin.py

@@ -6,14 +6,14 @@
 import pluggy
 
 from rasa.cli import SubParsersAction
-from rasa.engine.storage.storage import ModelMetadata
 from rasa.shared.core.trackers import DialogueStateTracker
 from rasa.shared.nlu.training_data.message import Message
 
 if TYPE_CHECKING:
     from rasa.core.brokers.broker import EventBroker
     from rasa.core.tracker_store import TrackerStore
     from rasa.engine.graph import SchemaNode
+    from rasa.engine.storage.storage import ModelMetadata
     from rasa.shared.core.domain import Domain
     from rasa.utils.endpoints import EndpointConfig
 
@@ -95,7 +95,7 @@ def init_telemetry(endpoints_file: Optional[Text]) -> None:
 
 @hookspec  # type: ignore[misc]
 def mock_tracker_for_evaluation(
-    example: Message, model_metadata: Optional[ModelMetadata]
+    example: Message, model_metadata: Optional["ModelMetadata"]
 ) -> Optional[DialogueStateTracker]:
     """Generate a mocked tracker for NLU evaluation."""