[issue34294] re.finditer and lookahead bug

[Ma Lin]

Ma Lin <malincns at 163.com> added the comment:

I tried to fix it, feel free to create a new PR if you don't want this one.

PR11546 has a small question, should `state->data_stack` be dealloced as well?

FYI, function `state_reset(SRE_STATE* state)` in file `_sre.c`:
https://github.com/python/cpython/blob/d4f9cf5545d6d8844e0726552ef2e366f5cc3abd/Modules/_sre.c#L340-L352

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