Update CHANGELOG

Author: bouwew

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Rework tooling [#664](https://github.com/plugwise/python-plugwise/pull/664)
 - Archive p1v4 userdata [#666](https://github.com/plugwise/python-plugwise/pull/666)
 - Correct manual_fixtures script [#668](https://github.com/plugwise/python-plugwise/pull/668)
+- Improve P1 fault-handling [#670](https://github.com/plugwise/python-plugwise/pull/670)
 
 ## v1.6.3