bpo-13337: Add ignore flag to doctest

[justinba1010]

Adds a flag to doctest that allows doctest to ignore case.

https://bugs.python.org/issue13337

[the-knights-who-say-ni]

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[justinba1010]

I can't figure out why it fails the Azure pipeline.

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[justinba1010]

I can sign the CLA, let me know if I can give a hand @serhiy-storchaka
Thanks for re-opening!

[serhiy-storchaka]

This looks interesting. Please add documentation and the What's New entry.

[python-cla-bot]

All commit authors signed the Contributor License Agreement.