Update dependency keycloak/keycloak to v21

defaults/main.yml

 ---
 # renovate: datasource=github-releases depName=keycloak/keycloak
-keycloak_version: 20.0.2
+keycloak_version: 21.0.1
 keycloak_dir: /var/keycloak
 keycloak_archive: keycloak-{{ keycloak_version }}.tar.gz
 keycloak_url: https://github.com/keycloak/keycloak/releases/download/{{ keycloak_version }}/{{ keycloak_archive }}