Update Moodle Plugin CI configuration to latest recommendation

.github/workflows/moodle-plugin-ci.yml

@@ -8,7 +8,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:9.6
+        image: postgres:10
         env:
           POSTGRES_USER: 'postgres'
           POSTGRES_HOST_AUTH_METHOD: 'trust'
@@ -16,7 +16,7 @@ jobs:
           - 5432:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 3
       mariadb:
-        image: mariadb:10
+        image: mariadb:10.5
         env:
           MYSQL_USER: 'root'
           MYSQL_ALLOW_EMPTY_PASSWORD: "true"
@@ -41,6 +41,8 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
+          extensions: ${{ matrix.extensions }}
+          ini-values: max_input_vars=5000
           coverage: none
 
       - name: Initialise moodle-plugin-ci