Bump typing-extensions from 4.1.1 to 4.2.0

Bumps [typing-extensions](https://github.com/python/typing) from 4.1.1 to 4.2.0.
- [Release notes](https://github.com/python/typing/releases)
- [Changelog](https://github.com/python/typing/blob/master/typing_extensions/CHANGELOG.md)
- [Commits](https://github.com/python/typing/compare/4.1.1...4.2.0)

---
updated-dependencies:
- dependency-name: typing-extensions
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -15,4 +15,4 @@ langdetect==1.0.9
 setproctitle==1.2.3
 redis==4.2.2
 markdown-it-py==2.1.0
-typing_extensions==4.1.1
+typing_extensions==4.2.0