fix: preview of mail not working on firefox

Author: tinect

composer.json

@@ -1,6 +1,6 @@
 {
     "name": "frosh/mail-platform-archive",
-    "version": "3.5.4",
+    "version": "3.5.5",
     "description": "Mail Archive",
     "type": "shopware-platform-plugin",
     "license": "MIT",

src/Resources/app/administration/src/module/frosh-mail-archive/page/frosh-mail-archive-detail/index.js

@@ -128,7 +128,7 @@ Component.register('frosh-mail-archive-detail', {
             binary.forEach(b => result += String.fromCharCode(b));
 
             return (
-                'data:text/html;base64;charset=utf-8,' + btoa(result)
+                'data:text/html;charset=utf-8;base64,' + btoa(result)
             );
         },
         openCustomer() {