Possible bug in `re` module in Python 3.11?

Hi, 
I would like to ask your guidance as I'm entirely sure whether the problem I'm experiencing should be posted in CPython's repo as a bug issue.
I've tried using newly released Python 3.11 interpreter in some of my projects and one of them failed to start with "RuntimeError: invalid SRE code" error.

Looking into implementation of one of the dependencies I've found out that the issue has been found out by a maintainer and fixed (https://github.com/pydicom/pydicom/issues/1658).
It looks like this particular regexp caused the `re.compile()` method to raise:

```
   re.compile(
        r"(?P<h>^([01][0-9]|2[0-3]))"
        r"((?P<m>([0-5][0-9]))?"
        r"(?(5)(?P<s>([0-5][0-9]|60))?)"
        r"(?(7)(\.(?P<ms>([0-9]{1,6})?))?))$"
    )
```

I've checked and this hasn't been an issue in all previous Python interpreter versions, starting from 3.6 (the oldest I've checked).
What's more the regex i correctly recognized and does not cause any issues in other regexp implementations, e.g. the online tool https://regex101.com/

Could somebody help me decide whether this is indeed a bug?

Best regards,
Piotr Waszkiewicz