Bump typing-extensions from 4.0.1 to 4.3.0

Bumps [typing-extensions](https://github.com/python/typing_extensions) from 4.0.1 to 4.3.0.
- [Release notes](https://github.com/python/typing_extensions/releases)
- [Changelog](https://github.com/python/typing_extensions/blob/main/CHANGELOG.md)
- [Commits](python/typing_extensions@4.0.1...4.3.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

setup.py

@@ -25,11 +25,11 @@
         # pip install -e ".[testing]"
         "testing": ['pytest'],
         ':python_version == "3.6"': [
-            "typing-extensions==4.0.1",
+            "typing-extensions==4.3.0",
             'dataclasses==0.8'
         ],
         ':python_version == "3.7"': [
-            "typing-extensions==4.0.1"
+            "typing-extensions==4.3.0"
         ]
     },
     tests_require=['pytest'],