`re.sub()` leaks references

[neonene]

Bug report

Bug description:

>python_d -X showrefcount -c "import re; re.sub(r'()', r'\1', '')"
[7140 refs, 4669 blocks]

_strptime is a module affected by this.

CPython versions tested on:

3.10, 3.11, 3.12, 3.13, CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-120244: Fix re.sub() reference leak #120245
• [3.13] gh-120244: Fix re.sub() reference leak (GH-120245) #120264
• [3.12] gh-120244: Fix re.sub() reference leak (GH-120245) #120265