Support for Python 3.12

[jorenham]

supersedes #122

[katdom13]

Hi @jorenham ,
This looks good. A suggestion would be to add the classifier for Python 3.12 in setup.py:
https://github.com/Frojd/wagtail-geo-widget/blob/main/setup.py#L60

And maybe add an entry on the CHANGELOG.md: https://github.com/Frojd/wagtail-geo-widget/blob/main/CHANGELOG.md

Thanks!

[jorenham]

@katdom13 Your suggestions have been implemented 👌🏻

[marteinn]

@jorenham Apologies, I missed this PR. Python 3.12 support has already been added, but I have included your regex fix in cceb38f. Also many thanks to @katdom13 for providing support and feedback.