keycloak: Downgrade to Java 11 (LTS)

Keycloak doesn't support Java 16 (yet)[1].

[1] https://issues.redhat.com/browse/KEYCLOAK-18307

roles/keycloak/tasks/main.yml

 ---
 
 - name: install keycloak
-  pacman: name=keycloak,keycloak-metrics-spi,python-passlib state=present
+  pacman: name=jre11-openjdk,keycloak,keycloak-metrics-spi,python-passlib state=present
 
 - name: template keycloak config
   template: src=standalone.xml.j2 dest=/etc/keycloak/standalone.xml owner=keycloak group=keycloak mode=600