docs: add changelog

Author: kenjis

user_guide_src/source/changelogs/v4.3.0.rst

@@ -12,6 +12,7 @@ Release Date: Unreleased
 Highlights
 **********
 
+- Update minimal PHP requirement to 8.0.
 - TBD
 
 BREAKING
@@ -305,6 +306,7 @@ Message Changes
 Changes
 *******
 
+- Update minimal PHP requirement to 8.0.
 - Config
     - All atomic type properties in ``Config`` classes have been typed.
 - Changed the processing of Spark commands: