Fix building solr

I kept hitting an error when building solr `/bin/sh: /docker-entrypoint.sh: Text file busy`, this is caused where the script is attempted to be ran before the previous `chmod` command has properly sync'd to disk. Adding in a sync fixes this trouble for me.
2019-02-15 17:04:53 +11:00 · 2019-02-15 17:04:53 +11:00 · 1355e993dd
commit 1355e993dd
parent 4d7f2618ad
1 changed files with 1 additions and 0 deletions
--- a/data/Dockerfiles/solr/Dockerfile
+++ b/data/Dockerfiles/solr/Dockerfile
@ -4,6 +4,7 @@ COPY docker-entrypoint.sh /

 RUN apk --no-cache add su-exec curl tzdata \
  && chmod +x /docker-entrypoint.sh \
+  && sync \
  && /docker-entrypoint.sh --bootstrap

 ENTRYPOINT ["/docker-entrypoint.sh"]