11.3.x core branch created

Migrated issue

Reported by: jonathan1055

Related to !419 (merged)

Problem/Motivation

The latest dev branch of Core is now 11.3.x released 24 October (previously just 11.x)

Proposed resolution

Update CORE_NEXT_MINOR from 11.x-dev to 11.3.x-dev as per the Check Versions recommendation