fix: Add conn.commit() to Postgresonline_write_batch.online_write_batch (feast-dev#3904)

Author: job-almekinders

sdk/python/feast/infra/online_stores/contrib/postgres.py

@@ -99,6 +99,7 @@ def online_write_batch(
                     cur_batch,
                     page_size=batch_size,
                 )
+                conn.commit()
                 if progress:
                     progress(len(cur_batch))