chore(deps): update prom/prometheus docker tag to v3

Author: renovate-gh-app-micxer[bot]

defaults/main.yml

@@ -37,7 +37,7 @@ homestack_nextcloud_base_domain: example.com
 homestack_monitoring_active: true
 homestack_monitoring_base_domain: example.com
 # renovate: image=prom/prometheus
-homestack_monitoring_prometheus_image_version: v2.55.1
+homestack_monitoring_prometheus_image_version: v3.4.2
 # homestack_monitoring_prometheus_base_path: ""  # must be set
 # renovate: image=grafana/grafana-oss
 homestack_monitoring_grafana_image_version: 11.6.1