EncodingWarning in faulthandler

With PYTHONWARNDEFAULTENCODING, pytest emits a warning on startup:

```
 jaraco.abode main $ env PYTHONWARNDEFAULTENCODING=1 .tox/py/bin/python -m pytest
/Users/jaraco/code/jaraco/jaraco.abode/.tox/py/lib/python3.11/site-packages/_pytest/faulthandler.py:30: EncodingWarning: 'encoding' argument not specified
  config.stash[fault_handler_stderr_key] = open(stderr_fd_copy, "w")
...
```