Update ELK images
elasticsearch:
- https://github.com/docker-library/elasticsearch/commit/5cabf94: Merge pull request https://github.com/docker-library/elasticsearch/pull/204 from infosiftr/eol
- https://github.com/docker-library/elasticsearch/commit/3e2c989: Remove eol version 6.x
logstash:
- https://github.com/docker-library/logstash/commit/6328b07: Merge pull request https://github.com/docker-library/logstash/pull/105 from infosiftr/eol
- https://github.com/docker-library/logstash/commit/91ddac9: Remove eol version 6.x
kibana:
- https://github.com/docker-library/kibana/commit/63fae4c: Merge pull request https://github.com/docker-library/kibana/pull/99 from infosiftr/eol
- https://github.com/docker-library/kibana/commit/dc8f4b0: Remove eol version 6.x
Docker Library Bot