Update Kernel

Author: TavoNiievez

composer.json

@@ -81,7 +81,8 @@
         "symfony/polyfill-php72": "*",
         "symfony/polyfill-php73": "*",
         "symfony/polyfill-php74": "*",
-        "symfony/polyfill-php80": "*"
+        "symfony/polyfill-php80": "*",
+        "symfony/polyfill-php81": "*"
     },
     "scripts": {
         "auto-scripts": {