message: Missed a character.
diff: @@ -9,7 +9,7 @@ RUN apk add --no-cache tini \
  fluent-plugin-elasticsearch \
  fluent-plugin-secure-forward \
  fluent-plugin-record-modifier \
  - && gem install fluent-plugin-prometheus --version='~0.4.0' \
  + && gem install fluent-plugin-prometheus --version='~>0.4.0' \
  && gem sources --clear-all \
  && apk del .build-deps \
  && rm -rf /var/cache/apk/* \
  