This is a backport of the BaseExceptionGroup and ExceptionGroup
classes from Python 3.11.

It contains the following:

    The exceptiongroup.BaseExceptionGroup and exceptiongroup.ExceptionGroup
    classes
    A utility function (exceptiongroup.catch()) for catching
    exceptions possibly nested in an exception group
    Patches to the TracebackException class that properly formats
    exception groups (installed on import)
    An exception hook that handles formatting of exception groups
    through TracebackException (installed on import)