Revert "Remove thermostat/setpoint from DEVICE_MEAS"

This reverts commit 8a4e88b.

Author: bouwew

plugwise/constants.py

@@ -448,6 +448,8 @@
 DEVICE_MEASUREMENTS: Final[dict[str, dict[str, str]]] = {
     # HA Core thermostat current_temperature
     "temperature": {ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS},
+    # HA Core thermostat setpoint
+    "thermostat": {ATTR_NAME: "setpoint", ATTR_UNIT_OF_MEASUREMENT: TEMP_CELSIUS},
     # Specific for an Anna
     "illuminance": {ATTR_UNIT_OF_MEASUREMENT: UNIT_LUMEN},
     # Specific for an Anna with heatpump extension installed