MBS-10134: Update GHA

Author: PhMemmel

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
       fail-fast: false
       matrix:
         php: ['8.2', '8.3']
-        moodle-branch: ['main', 'MOODLE_500_STABLE', 'MOODLE_405_STABLE']
+        moodle-branch: ['main', 'MOODLE_500_STABLE']
         database: [pgsql, mariadb]
 
     steps: