Reset state on error during VOIP announcement (home-assistant#156384)

Author: jaminh

homeassistant/components/voip/assist_satellite.py

@@ -492,6 +492,7 @@ async def _play_announcement(
                 await asyncio.sleep(_ANNOUNCEMENT_AFTER_DELAY)
         except Exception:
             _LOGGER.exception("Unexpected error while playing announcement")
+            self._announcement = None
             raise
         finally:
             self._run_pipeline_task = None