Update azul/zulu-openjdk-alpine Docker tag to v21.0.8

Author: renovate[bot]

Dockerfile

@@ -1,3 +1,3 @@
-FROM azul/zulu-openjdk-alpine:21.0.7
+FROM azul/zulu-openjdk-alpine:21.0.8
 COPY build/libs/consumer-0.0.1-SNAPSHOT.jar app.jar
 ENTRYPOINT ["java","-jar","/app.jar"]