Add async loading to script

Resources/Private/Fusion/Root.fusion

@@ -23,6 +23,7 @@ prototype(Medienreaktor.CookieConsent) < prototype(Neos.Fusion:Array) {
         tagName = 'script'
         attributes {
             type = 'text/javascript'
+            async = 'true'
             src = Neos.Fusion:ResourceUri {
                 path = 'resource://Medienreaktor.CookieConsent/Public/JavaScript/cookieconsent.min.js'
             }