Fix asyncio retry.py typing

[Andrew-Chen-Wang]

Pull Request check-list

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• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Is the changes added to CHANGES file?

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afterwards / while the PR is open.

Description of change

Please provide a description of the change here.

[dvora-h]

Thanks for this! @Andrew-Chen-Wang