Bump typing-extensions from 4.1.1 to 4.2.0 in /dependencies/default (#336)

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](python/typing@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>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

dependencies/default/constraints.txt

@@ -20,5 +20,5 @@ sortedcontainers==2.4.0
 tomli==2.0.1
 trio==0.20.0
 typed-ast==1.5.3
-typing_extensions==4.1.1
+typing_extensions==4.2.0
 zipp==3.8.0