Python 3.8 is now end-of-life, receiving no further updates, and so at some point we may also need to drop support for it.

Out current version-compatibility policy suggests an approximate grace period of 6 months before actually implementing the upgrade, so I wonder if now is a good time to introduce a deprecation warning for users who are still operating on python 3.8 so that they have some notice to be able to make upgrades if possible (if they wish to continue to get new Splink versions).

It may well be that we don't need to update the dependency until much later than that. I don't think we really need to take responsibility for ensuring people are using supported python versions, so I think we can probably leave 3.8 in pyproject.toml until:

• we hit issues with our dependencies being compatible with this version
• we decide it would be highly beneficial to make use of some language feature not introduced until 3.9
• it becomes too much work to keep this version working properly (as happened previously with 3.7 and 3.6)
• some combination of the above

I realise we will have some users who won't be able to upgrade their version of python, but this will only stop them being able to get new Splink versions. Hopefully with this period of deprecation they have time to request features / report bugs that can be addressed before we drop support.

Happy to hear any other opinions on this!