minor: fix user-agent string.

acme.sh

@@ -633,9 +633,9 @@ _post() {
     _CURL="$CURL --dump-header $HTTP_HEADER "
     _debug "_CURL" "$_CURL"
     if [ "$needbase64" ] ; then
-      response="$($_CURL -A "User-Agent: $USER_AGENT" -X $httpmethod -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" --data "$body" "$url" | _base64)"
+      response="$($_CURL --user-agent "$USER_AGENT" -X $httpmethod -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" --data "$body" "$url" | _base64)"
     else
-      response="$($_CURL -A "User-Agent: $USER_AGENT" -X $httpmethod -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" --data "$body" "$url" )"
+      response="$($_CURL --user-agent "$USER_AGENT" -X $httpmethod -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" --data "$body" "$url" )"
     fi
     _ret="$?"
   else
@@ -670,9 +670,9 @@ _get() {
   if _exists "curl" ; then
     _debug "CURL" "$CURL"
     if [ "$onlyheader" ] ; then
-      $CURL -I -A "User-Agent: $USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" $url
+      $CURL -I --user-agent "$USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" $url
     else
-      $CURL    -A "User-Agent: $USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" $url
+      $CURL    --user-agent "$USER_AGENT" -H "$_H1" -H "$_H2" -H "$_H3" -H "$_H4" $url
     fi
     ret=$?
   else