message: fix: limit the elasticsearch gem version
  Version 7.14 and above are no longer compatible with Opensearch.
diff: @@ -8,6 +8,7 @@ USER root
  RUN apk add --no-cache --update --virtual .build-deps \
  build-base ruby-dev \
  + && gem install elasticsearch -v '< 7.14' \
  && gem install fluent-plugin-elasticsearch \
  && gem install fluent-plugin-prometheus \
  && gem sources --clear-all \
  