Update ELK images
elasticsearch:
- https://github.com/docker-library/elasticsearch/commit/323a902: Update to 7.6.2
- https://github.com/docker-library/elasticsearch/commit/79420fb: Update to 6.8.8
logstash:
- https://github.com/docker-library/logstash/commit/c75adbe: Update to 7.6.2
- https://github.com/docker-library/logstash/commit/591ffb5: Update to 6.8.8
kibana:
- https://github.com/docker-library/kibana/commit/8e76f48: Update to 7.6.2
- https://github.com/docker-library/kibana/commit/119c1cd: Update to 6.8.8
Docker Library Bot