Flags no longer regonised by PyLint

[julianstirling]

PyLint now throws an error when using flags in regex, see issue raised in PyLint.

Rolling back pylint does nothing to fix this. Rolling back regex to 2022.1.18 does fix it. It seems that the commit that introduces the issue is 67ab717

[encukou]

This should be now fixed in pylint (or rather, its dependency: pylint-dev/astroid#1911)