Update Changelog

Author: bouwew

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Remove `schedule_temperature` from output: for Adam the schedule temperature cannot be collected when a schedule is not active.
 - Simplify `_schedules()`, don't collect the schedule-details as no longer required.
 - Improve solution for plugwise-beta issue #276
+- Move HA Core input-checks into the backend library (into set_schedule_state() and set_preset())
 
 # v0.18.3: Smile: move solution for https://github.com/plugwise/plugwise-beta/issues/276 into backend