Update quay.io/keycloak/keycloak Docker tag to v26

Author: renovate[bot]

docker-compose.yml

@@ -9,7 +9,7 @@ services:
   keycloak:
     # Starting with Keycloak 17, Keycloak is now powered by Quarkus and no longer WildFly
     # This requires slight changes to the configuration, see https://www.keycloak.org/migration/migrating-to-quarkus
-    image: quay.io/keycloak/keycloak:18.0.2
+    image: quay.io/keycloak/keycloak:26.6.1
     command: [ 'start-dev --http-relative-path /auth --import-realm --auto-build' ]
     environment:
       - KEYCLOAK_DB=dev-file

src/test/java/de/rieckpil/courses/TestcontainersConfig.java

@@ -61,7 +61,7 @@ public LocalStackContainer localStack() {
 
   @Bean
   GenericContainer<?> keycloakContainer() {
-    return new GenericContainer<>(DockerImageName.parse("quay.io/keycloak/keycloak:18.0.2"))
+    return new GenericContainer<>(DockerImageName.parse("quay.io/keycloak/keycloak:26.6.1"))
         .withCommand("start-dev", "--http-relative-path", "/auth", "--import-realm")
         .withEnv("KEYCLOAK_DB", "dev-file")
         .withEnv("KEYCLOAK_ADMIN", "keycloak")