Prefer keras from tensorflow instead of standalone keras in model adapter

Author: constantinpape

bioimageio/core/prediction_pipeline/_model_adapters/_keras_model_adapter.py

@@ -1,7 +1,10 @@
 import warnings
 from typing import List, Optional, Sequence
 
-import keras
+try:
+    from tensorflow import keras
+except Exception:
+    import keras
 import xarray as xr
 
 from ._model_adapter import ModelAdapter