add additional Moodle versions

Author: dlandau

.github/workflows/moodle-ci.yml

@@ -31,7 +31,7 @@ jobs:
       fail-fast: false
       matrix:
         php: ['8.2']
-        moodle-branch: ['MOODLE_405_STABLE']
+        moodle-branch: ['MOODLE_405_STABLE','MOODLE_500_STABLE','MOODLE_501_STABLE','main']
         database: [pgsql, mariadb]
 
     steps: