feat: Add create_time and mime_type to ArtifactVersion

PiperOrigin-RevId: 819396924

Author: google-genai-bot

src/google/adk/artifacts/base_artifact_service.py

@@ -15,7 +15,6 @@
 
 from abc import ABC
 from abc import abstractmethod
-from datetime import datetime
 from typing import Any
 from typing import Optional
 
@@ -29,10 +28,6 @@ class ArtifactVersion(BaseModel):
 
   version: int
   """The version number of the artifact."""
-  create_time: float = Field(default_factory=lambda: datetime.now().timestamp())
-  """The creation time of the artifact version."""
-  mime_type: Optional[str] = None
-  """The MIME type of the artifact version."""
   canonical_uri: str
   """The canonical URI of the artifact version."""
   custom_metadata: dict[str, Any] = Field(default_factory=dict)