Fix for Honeywell Round thermostats (#9308)

This fixes an issue (#8554) whereby the Honeywell thermostats stopped
working after a period of hours or days. We do this by forgetting the
authorisation token that was sent back to us when we first logged in,
which causes the underlying evohomeclient library to perform the full
login procedure again.

homeassistant/components/climate/honeywell.py

@@ -196,6 +196,11 @@ class RoundThermostat(ClimateDevice):
                 if val['id'] == self._id:
                     data = val
 
+        except KeyError:
+            _LOGGER.error("Update failed from Honeywell server")
+            self.client.user_data = None
+            return
+
         except StopIteration:
             _LOGGER.error("Did not receive any temperature data from the "
                           "evohomeclient API")