chore: update error message and replace deprecated logger.warn method (#143)

* chore: update error message and replace deprecated logger.warn method

* formatting

Author: shubha-rajan

google/cloud/sql/connector/instance_connection_manager.py

@@ -387,9 +387,9 @@ def _refresh_callback(task: asyncio.Task) -> None:
             try:
                 task.result()
             except Exception as e:
-                logger.warn(
-                    "An error occurred while performing refresh. Retrying immediately.",
-                    e,
+                logger.exception(
+                    "An error occurred while performing refresh. Retrying in 60s.",
+                    exc_info=e,
                 )
                 instance_data = None
                 try: