Update typing-extensions requirement from >=4.5.0 to >=4.15.0

Updates the requirements on [typing-extensions](https://github.com/python/typing_extensions) to permit the latest version.
- [Release notes](https://github.com/python/typing_extensions/releases)
- [Changelog](https://github.com/python/typing_extensions/blob/main/CHANGELOG.md)
- [Commits](python/typing_extensions@4.5.0...4.15.0)

---
updated-dependencies:
- dependency-name: typing-extensions
  dependency-version: 4.15.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

requirements-dev.txt

@@ -12,5 +12,5 @@ wheel
 rellu >= 0.7
 twine
 wheel
-typing-extensions >= 4.5.0
+typing-extensions >= 4.15.0
 approvaltests >= 17.4.3