use async for script tag

Author: ssachtleben

styla.php

@@ -68,7 +68,7 @@ public function getMagazineMetaTags() {
         public function getLPMetaTags() {
             return join([
                 "<link rel=\"preconnect\" href=\"https://engine.styla.com\">",
-                "<script src=\"", self::$prophetUrl, "\"></script>"
+                "<script src=\"", self::$prophetUrl, "\" async></script>"
             ]);
         }
 
@@ -266,4 +266,4 @@ private function buildContentKey() {
         private function init() {
             $this->buildContentKey();
         }
-    }
+    }