chore: suppress dos2unix stderr output during Dockerfile builds

plugins/builder-dockerfile/builder-build

@@ -33,7 +33,7 @@ trigger-builder-dockerfile-builder-build() {
   fi
 
   # extract first port from Dockerfile
-  dos2unix Dockerfile
+  suppress_output dos2unix Dockerfile
   local DOCKERFILE_PORTS=$(get_dockerfile_exposed_ports Dockerfile)
   [[ -n "$DOCKERFILE_PORTS" ]] && config_set --no-restart "$APP" DOKKU_DOCKERFILE_PORTS="$DOCKERFILE_PORTS"
   plugn trigger pre-build-dockerfile "$APP"