use mariadb for testing

.gitlab-ci.yml

@@ -8,8 +8,15 @@ test:
     DJANGO_SETTINGS_MODULE: foerderbarometer.settings
     ENVIRONMENT: test
     SECRET_KEY: this-is-not-a-secret-key
-    DATABASE_ENGINE: sqlite3
+    DATABASE_ENGINE: mysql
+    DATABASE_HOST: mariadb
+    DATABASE_USER: root
+    DATABASE_PASSWORD: fdb
     OAUTH_ENABLED: no
+  services:
+    - name: mariadb:10.6
+      variables:
+        MARIADB_ROOT_PASSWORD: fdb
   tags:
     - docker
   coverage: /(?i)total.*? (100(?:\.0+)?\%|[1-9]?\d(?:\.\d+)?\%)$/