chore: Updated test to include join_key (#4587)

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

sdk/python/tests/unit/online_store/test_online_writes.py

@@ -103,7 +103,7 @@ def test_view(inputs: dict[str, Any]) -> dict[str, Any]:
                 ]
             )
             # after apply() join_keys is [driver]
-            assert driver_stats_fv.join_keys == [driver]
+            assert driver_stats_fv.join_keys == [driver.join_key]
             self.store.write_to_online_store(
                 feature_view_name="driver_hourly_stats", df=driver_df
             )