chore(deps): update docker.elastic.co/beats/metricbeat docker tag to v8.15.3

Author: renovate[bot]

infrastructure/docker-compose.dependencies.yml

@@ -89,7 +89,7 @@ services:
         - 'traefik.enable=false'
 
   metricbeat:
-    image: docker.elastic.co/beats/metricbeat:8.14.3
+    image: docker.elastic.co/beats/metricbeat:8.15.3
     networks:
       - elasticsearch_net
     user: root