fix: remove 'anonymous' security in JWT config (#1447)

The anonymous option for the firewall config was removed in symfony 5.1
as explained here: symfony/symfony#36574

Using the option caused an error but it can be skipped. "[A] user that
is not authenticated is similar to an "unknown" user: They both have no
rights at all."

Resolves #1445

Author: wiese

core/jwt.md

@@ -84,7 +84,6 @@ security:
             security: false
         main:
             stateless: true
-            anonymous: true
             provider: app_user_provider
             json_login:
                 check_path: /authentication_token