Remove PHP 8.1 from testing matrix

Author: martignoni

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['8.1', '8.2']
+        php: ['8.2']
         moodle-branch: ['MOODLE_404_STABLE', 'MOODLE_405_STABLE', 'MOODLE_500_STABLE']
         database: [pgsql, mariadb]