fix: set default scheme correctly

plugins/haproxy-vhosts/docker-args-process-deploy

@@ -76,6 +76,7 @@ trigger-haproxy-vhosts-docker-args-process-deploy() {
   # add the labels for haproxy here
   # prefer the https:443 mapping to http:80 mapping
   if [[ -n "$is_app_listening" ]] && [[ -n "$haproxy_domains" ]]; then
+    scheme="http"
     echo "# THIS FILE IS GENERATED BY DOKKU - DO NOT EDIT, YOUR CHANGES WILL BE OVERWRITTEN" >"$app_urls_path"
     xargs -I{} echo "$scheme://{}" <<<"$(echo "${app_domains}" | tr ' ' '\n' | sort -u)" >>"$app_urls_path"
   fi