Put USER directive after chmod

pica-mattermost/Dockerfile

@@ -33,8 +33,6 @@ RUN mkdir -p /mattermost/data /mattermost/plugins /mattermost/client/plugins \
     && chown -R mattermost:mattermost /mattermost /config.json.save /mattermost/plugins /mattermost/client/plugins \
     && setcap cap_net_bind_service=+ep /mattermost/bin/mattermost
 
-USER mattermost
-
 #Healthcheck to make sure container is ready
 HEALTHCHECK --interval=5m --timeout=3s CMD curl --fail http://localhost:8000//api/v4/system/ping || exit 1
 
@@ -44,6 +42,8 @@ ENTRYPOINT ["/entrypoint.sh"]
 
 RUN chmod +x /entrypoint.sh
 
+USER mattermost
+
 WORKDIR /mattermost
 CMD ["mattermost"]