update(deps): update quay.io/keycloak/keycloak docker tag to v26

Author: renovate[bot]

docker-compose.yml

@@ -25,7 +25,7 @@ services:
       - "host.docker.internal:host-gateway"
 
   keycloak:
-    image: quay.io/keycloak/keycloak:21.1.1
+    image: quay.io/keycloak/keycloak:26.5.2
     environment:
       - KEYCLOAK_ADMIN=admin
       - KEYCLOAK_ADMIN_PASSWORD=admin