fix: use exception group for autosummary import errors

[flying-sheep]

Purpose

Since the MRPV is 3.11, we can just use the BaseExceptionGroup class as base class for the ImportExceptionGroup, which will result in much more context being included in the traceback.

This allows people to more easily debug why autosummary fails when it does.

References

• Fixes Autosummary import exception message is misleading and missing context #14056
• Closes Improve error message for import exception group #14057

[AA-Turner]

@flying-sheep thanks for the PR! Tests are failing, please can you also add a changed entry?

A

[flying-sheep]

All done! I’m excited, this was one of my first big usability issues with Sphinx, and soon it’ll be gone forever!