fix: set upper version bound of ckeditor/ckeditor to <4.22.0

Versions >=4.22.0 show a warning that the editor is insecure

Related: #37

composer.json

@@ -17,7 +17,7 @@
   "require": {
     "quiqqer\/quiqqer": "*",
     "quiqqer\/qui": ">=1|*@dev",
-    "ckeditor\/ckeditor": ">=4.16.0 <=4.22.1"
+    "ckeditor\/ckeditor": ">=4.16.0 <4.22.0"
   },
   "autoload": {
     "psr-4": {