Fix missing typing_extensions dependency

[donlon]

Description

Fixes #2036

Motivation and Context

How Has This Been Tested?

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added the changelog accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codspeed-hq]

CodSpeed Performance Report

Merging #2039 will not alter performance

_{Comparing donlon:typing-extensions (d3d82bd) with develop (dd9f9c5)}

Summary

✅ 16 untouched

[coveralls]

Pull Request Test Coverage Report for Build 20208414450

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 90.729%

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Totals
Change from base Build 20169305593:	0.0%
Covered Lines:	6633
Relevant Lines:	7196

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💛 - Coveralls