chore(deps): update docker.io/library/mariadb docker tag to v10.11.15 (#1567)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

library/compose/nextcloud/compose.yaml.j2

@@ -75,7 +75,7 @@ services:
     {% if database_type == 'mysql' %}
     # See compatibility matrix for Nextcloud 31
     # https://docs.nextcloud.com/server/31/admin_manual/installation/system_requirements.html
-    image: docker.io/library/mariadb:10.11.14
+    image: docker.io/library/mariadb:10.11.15
     {% if not swarm_enabled %}
     restart: {{ restart_policy }}
     container_name: {{ service_name }}-db