fix: set mariadb capabilities instead of defining user

Signed-off-by: rare-magma <rare-magma@posteo.eu>

docker-compose example/docker-compose.example.yml

@@ -116,12 +116,16 @@ services:
     container_name: photoview-mariadb
     restart: unless-stopped
     stop_grace_period: 5s
-    user: "999:999"
     ## Optimized MariaDB startup command for better performance and compatibility
     command: mariadbd --innodb-buffer-pool-size=512M --transaction-isolation=READ-COMMITTED --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci --max-connections=512 --innodb-rollback-on-timeout=OFF --innodb-lock-wait-timeout=120
     ## Security options for some restricted systems
     cap_drop:
       - ALL
+    cap_add:
+      - CHOWN
+      - DAC_READ_SEARCH
+      - SETUID
+      - SETGID
     security_opt:
       - no-new-privileges:true
      # not necessary since Docker Engine v20 see https://github.com/MariaDB/mariadb-docker/issues/434#issuecomment-1136151239