add changelog for 4.2.3

Author: lonvia

ChangeLog

@@ -30,6 +30,13 @@
  * modernize Python code around BDD test and add testing of Python frontend
  * lots of new BDD tests for API output
 
+4.2.3
+
+ * fix deletion handling for 'nominatim add-data'
+ * adapt place_force_delete() to new deletion handling
+ * flex style: avoid dropping of postcode areas
+ * fix update errors on address interpolation handling
+
 4.2.2
 
  * extend flex-style library to fully support all default styles