Update config_flow.py

Fix typo in @callback: 
`in_progess_instances` -> `in_progress_instances`

custom_components/alexa_media/config_flow.py

@@ -84,7 +84,7 @@ def configured_instances(hass):
 
 
 @callback
-def in_progess_instances(hass):
+def in_progress_instances(hass):
     """Return a set of in progress Alexa Media flows."""
     return {entry["flow_id"] for entry in hass.config_entries.flow.async_progress()}