add typing_extensions as test dependencies which is required by modelopt

[lanluo-nvidia]

Description

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Fixes # (issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

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• I have performed a self-review of my own code
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• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
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[narendasan]

LGTM

[narendasan]

At some point can we move to these being recorded as a group in pyproject.toml instead of in here?

[narendasan]

Post 2.8