Bump typing-extensions from 3.7.4.2 to 3.7.4.3 (#41)

Bumps [typing-extensions](https://github.com/python/typing) from 3.7.4.2 to 3.7.4.3.
- [Release notes](https://github.com/python/typing/releases)
- [Commits](python/typing@3.7.4.2...3.7.4.3)

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

Author: dependabot[bot]

requirements.txt

@@ -5,5 +5,5 @@ mypy==0.782
 pycodestyle==2.6.0
 pyflakes==2.2.0
 typed-ast==1.4.1
-typing-extensions==3.7.4.2
+typing-extensions==3.7.4.3
 wheel==0.35.1