To answer to myself ( and may be it cant help other)
you can have auth headers to requests with
var auth=str("Basic ", Marshalls.utf8_to_base64(str(user, ":", password)))
var headers=["Content-Type: application/json","Authorization: "+auth]
HTTPRequest.request("https://www.yousite.com", headers, ssl_true, HTTPClient.METHOD_POST, query)
it's working but have an error parsing the answer :
godot give me a
ERROR: readresponsebodychuck: Condition "status != STATUSBODY" is true
i try the same request with postman , and it's work ....
any idea ?