tracebacks: Handle ExceptionGroup

[sscherfke]

Fixes: #676

Summary

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[sscherfke]

@hynek ping :)

[hynek]

it looks like the tests are failing on Python 3.14 – could you have a look pls? (make sure you've got b2)

[sscherfke]

Error message for 1 // 0 in the lastest 3.14 release. Fixed it.

[hynek]

thanks!