chore: Bump fallback GCS version to 3.0.0 in tests, in accordance with the recent GCS version update

PiperOrigin-RevId: 892087422

Author: vertex-sdk-bot

google/cloud/aiplatform/utils/gcs_utils.py

@@ -45,7 +45,7 @@
     _GCS_VERSION = Version(get_version("google-cloud-storage"))
 except Exception:
     # Fallback if version detection fails (should not happen in normal use)
-    _GCS_VERSION = Version("2.0.0")
+    _GCS_VERSION = Version("3.0.0")
 
 _USE_FROM_URI = _GCS_VERSION >= Version("3.0.0")