[Feature]: Add ExceptionGroup support

[tsv1]

Summary

Enhance error reporting by adding support for Python's ExceptionGroup (PEP 654). Improve clarity and usability of traceback outputs for grouped exceptions.

Problem

Currently, ExceptionGroup displays only a summary:

Scenarios
*
 ✗ login as user
   ✗ when
╭────────────────────────── Traceback (most recent call last) ───────────────────────────╮
│ /scenarios/login_as_user.py:9 in when                                                  │
│                                                                                        │
│    6     subject = "login as user"                                                     │
│    7                                                                                   │
│    8     def when(self):                                                               │
│ ❱  9         raise_exc_group()                                                         │
│   10                                                                                   │
╰────────────────────────────────────────────────────────────────────────────────────────╯
ExceptionGroup: Exception (2 sub-exceptions)

This lacks detailed information about sub-exceptions, making debugging challenging in scenarios with multiple errors.

Proposal

• Expand ExceptionGroup output to show individual sub-exceptions with full tracebacks.
• Use clear formatting to separate and label sub-exceptions.

Backward Compatibility Notes

• Non-ExceptionGroup exceptions remain unaffected.

[tsv1]

This feature is blocked by the following issue in the rich library: Support for PEP 654 tracebacks (ExceptionGroups) #1859.

[tsv1]

As a workaround, the following commit was added to Vedro: 4452a49. It disables pretty printing of ExceptionGroup in Python 3.11 and later, falling back to the default exception formatting.

[tsv1]

💡 Reminder: Ensure exception notes (Exception.add_note(...) from Python 3.11) are displayed in the enhanced ExceptionGroup traceback.