docs: correct CI badge reference

Author: keevan

README.md

@@ -1,6 +1,6 @@
 # moodle-tool_forcedcache
 
-![GitHub Workflow Status (branch)](https://img.shields.io/github/actions/workflow/status/catalyst/moodle-tool_forcedcache/ci.yml?label=ci&branch=MOODLE_40_STABLE)
+![GitHub Workflow Status (branch)](https://img.shields.io/github/actions/workflow/status/catalyst/moodle-tool_forcedcache/ci.yml?label=ci&branch=MOODLE_405_STABLE)
 
 * [What is this?](#what-is-this)
 * [Branches](#branches)