Properly handle json_array type removal

The `json_array` type was removed from DBAL v3, we should handle it using a migration to avoid error.
I've also added the remove type because we need it during migration.

src/Wallabag/UserBundle/Entity/User.php

@@ -128,6 +128,8 @@ class User extends BaseUser implements EmailTwoFactorInterface, GoogleTwoFactorI
     private $googleAuthenticatorSecret;
 
     /**
+     * @var array
+     *
      * @ORM\Column(type="json", nullable=true)
      */
     private $backupCodes;