fix: correct UUIDType partition representation for BucketTransform

Author: dingo4dev

pyiceberg/partitioning.py

@@ -467,8 +467,15 @@ def _(type: IcebergType, value: Optional[time]) -> Optional[int]:
 
 
 @_to_partition_representation.register(UUIDType)
-def _(type: IcebergType, value: Optional[uuid.UUID]) -> Optional[str]:
-    return str(value) if value is not None else None
+def _(type: IcebergType, value: Optional[Union[uuid.UUID,int]]) -> Optional[str|int]:
+    if value is None: 
+        return None
+    if isinstance(value, uuid.UUID):
+        return str(value) # IdentityTransform
+    elif isinstance(value, int):
+        return value # BucketTransform
+    else:
+        return value
 
 
 @_to_partition_representation.register(PrimitiveType)