Bump elasticsearch from 7.6.0 to 7.7.0 (#13784)

Bump elasticsearch from 7.6.0 to 7.7.0 (#13784)

Bumps [elasticsearch](https://github.com/elastic/elasticsearch-ruby) from 7.6.0 to 7.7.0.
- [Release notes](https://github.com/elastic/elasticsearch-ruby/releases)
- [Changelog](https://github.com/elastic/elasticsearch-ruby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/elastic/elasticsearch-ruby/compare/v7.6.0...7.7.0)

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