feat(Dependencies): Update haproxy Docker tag to v2.6.6

| datasource | package | from  | to    |
| ---------- | ------- | ----- | ----- |
| docker     | haproxy | 2.6.4 | 2.6.6 |

docker-compose.site.yml

@@ -51,7 +51,7 @@ services:
     # use the one below to have haproxy debug log directly to stdout including
     # every request with auth headers
     # image: mminks/haproxy-docker-logging:latest
-    image: "haproxy:2.6.4-alpine"
+    image: "haproxy:2.6.6-alpine"
     # use self build Dockerfile as alternative
     # build: prod/haproxy
     container_name: project_usage_proxy