add renovate snippet

Author: razvan

spark-k8s/Dockerfile

@@ -135,6 +135,8 @@ ARG JMX_EXPORTER
 ARG TARGETARCH
 ARG TINI
 ARG STACKABLE_USER_UID
+# Find the latest version here: https://github.com/apache/maven
+# renovate: datasource=github-tags packageName=apache/maven
 ARG MAVEN_VERSION="3.9.8"
 
 WORKDIR /stackable/spark-${PRODUCT}