Update dependency grafana/grafana to v8.5.6 (#228)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

definition/docker-compose.yml

@@ -19,7 +19,7 @@ services:
         restart: unless-stopped
 
     grafana:
-        image: 'grafana/grafana:8.5.5'
+        image: 'grafana/grafana:8.5.6'
         environment:
             - 'GF_SECURITY_ADMIN_USER=${ADMIN_USER:-admin}'
             - 'GF_SECURITY_ADMIN_PASSWORD=${ADMIN_PASSWORD:-admin}'