id card request : decode altcha payload

src/State/Provider/IdCardRequestProvider.php

@@ -45,7 +45,7 @@ class IdCardRequestProvider implements ProviderInterface
 
         try {
             $valid = Altcha::verifySolution(
-                $altchaPayload,
+                urldecode($altchaPayload),
                 $this->hmacKey,
                 true
             );