Bump elasticsearch from 7.6.0 to 7.7.0 (#1573)

Bumps [elasticsearch](https://github.com/elastic/elasticsearch-py) from 7.6.0 to 7.7.0.
- [Release notes](https://github.com/elastic/elasticsearch-py/releases)
- [Changelog](https://github.com/elastic/elasticsearch-py/blob/master/Changelog.rst)
- [Commits](https://github.com/elastic/elasticsearch-py/compare/7.6.0...7.7.0)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

extra-nlp-requirements.txt

@@ -1,4 +1,4 @@
-elasticsearch==7.6.0
+elasticsearch==7.7.0
 gensim==3.8.3
 nltk==3.5
 pyemd==0.5.1