Mariadb with docker-compose - db owner

Hi,
I try to move to mariadb with docker-compose.
When I start the database, the database directory is owned by homeassistant:spi.
How would I define another owner?
Here my docker-compose.yaml:

    mariadb:
      image: jsurf/rpi-mariadb
      container_name: mariadb
      restart: unless-stopped
      volumes:
        - /home/pi/docker/mariadb:/var/lib/mysql
        - /home/pi/docker/mariadb:/etc/mysql/conf.d
      environment:
        - PUID=1000
        - GUID=1000
        - TZ=Europe/Berlin
        - MYSQL_ROOT_PASSWORD=hajo
        - MYSQL_USER=pi
        - MYSQL_PASSWORD=hajo
        - MYSQL_DATABASE=homeassistantdb
      ports:
        - 3306:3306

It’s the same result with PUID/GUID set or not…

Nobody an idea, why the owner is not pi?