[Flask-Cors] Update type annotation for origins to also allow Pattern

[wvanbergen]

Small fix: this updates the type annotation for the origins argument for CORS() and CORS.init_app to also accept Patterns. Also, use Iterable rather than list to not cause compatibility issues.

• This reflects the typing of the origins argument of the cross_origin decorator.
• This matches the documentation: https://corydolphin.github.io/flask-cors/extension/
• This reflects what we have been running in production for many years.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[brianschubert]

Thanks! See remarks below. This change looks good, but I'm noticing some inconsistencies with the previous annotations that we should fix while we're here.

[wvanbergen]

@brianschubert I double-checked your suggestions, and they all makes sense, so committed your suggestions. Thanks!

[wvanbergen]

Something weird happened with the mypy_primer run - seems like either something transient, or something unrelated to my changes, but I cannot retry failed runs.