Update .env.docker

Updated DOCKER_PROXY_VERSION in .env

.env.docker

@@ -1270,7 +1270,7 @@ DOCKER_WORKER_HEALTHCHECK_INTERVAL="${DOCKER_ALL_DEFAULT_HEALTHCHECK_INTERVAL:?e
 #
 # @see https://hub.docker.com/r/nginxproxy/nginx-proxy
 # @dottie/validate required
-DOCKER_PROXY_VERSION="1.4"
+DOCKER_PROXY_VERSION="1.6"
 
 # How often Docker health check should run for [proxy] service
 # @dottie/validate required