Update ELK images
elasticsearch:
- https://github.com/docker-library/elasticsearch/commit/c2f5a01: Update to 7.5.1
- https://github.com/docker-library/elasticsearch/commit/4c04ee8: Update to 6.8.6
logstash:
- https://github.com/docker-library/logstash/commit/8285a96: Update to 7.5.1
- https://github.com/docker-library/logstash/commit/befe697: Update to 6.8.6
kibana:
- https://github.com/docker-library/kibana/commit/f6ea089: Update to 7.5.1
- https://github.com/docker-library/kibana/commit/581e38e: Update to 6.8.6
Docker Library Bot