Replace Optional[T] and Union[T, None] with T | None

[yangdanny97]

Summary

The pipe syntax for unions introduced in PEP604 is more concise than Optional, but it only works in Python 3.10+

This PR updates the rule replacing Union[T | None] with Optional[T] to replace both with T | None.

Test Plan

make

[bowiechen]

looks good! thank you for working on this.

please fix some nits and we can merge this.

[bowiechen]

you should merge these into the existing config dicts.

[meta-cla]

Hi @yangdanny97!

Thank you for your pull request.

We require contributors to sign our Contributor License Agreement, and yours needs attention.

You currently have a record in our system, but the CLA is no longer valid, and will need to be resubmitted.

Process

In order for us to review and merge your suggested changes, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

Once the CLA is signed, our tooling will perform checks and validations. Afterwards, the pull request will be tagged with CLA signed. The tagging process may take up to 1 hour after signing. Please give it that time before contacting us about it.

If you have received this in error or have any questions, please contact us at cla@meta.com. Thanks!