Adjusts WP's email validation regex syntax to JS

assets/js/src/subscribers/importExport/import.js

@@ -324,7 +324,7 @@ define(
                     email = test[1].trim();
                   }
                   // test for valid characters using WP's rule (https://core.trac.wordpress.org/browser/tags/4.7.3/src/wp-includes/formatting.php#L2902)
-                  if (!/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-@]+$/.test(email) ) {
+                  if (!/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.\-@]+$/.test(email) ) {
                     return false;
                   }
                   return email;