Update CHANGELOG

CHANGELOG

+v4.5.0
+* Improve tests and add option for remote tests 
+* Include PI in Mag/Ang format with calibration
+
+v4.4.0
+* New set of changes on PV names
+
+v4.3.0
+* New set of changes on PV names
+
+v4.2.0
+* Fix PV names
+* Fix labels for OpenLoop
+
+v4.1.1
+* Small fixes for PV names
+
+v4.1.0
+* Include iocsh file to be used by LLRF IOC
+
+v4.0.0
+* Include Loop Mode
+* Change PV names to follow ESS naming convention
+* Remove unused PVs
+* Split RTM and Digitiser PVs
+
 v3.17.0
 * Improve tests
 * Add Unified PI controllers to I/Q components