ci: isort deprecation warning

[terriko]

Not sure if this is something we can fix or if it's something that has to be done by isort, but here's the deprecation message:

Warning: repo [https://github.com/pycqa/isort](https://github.com/pycqa/isort%60) uses deprecated stage names (commit, merge-commit, push) which will be removed in a future version. Hint: often pre-commit autoupdate --repo [https://github.com/pycqa/isort](https://github.com/pycqa/isort%60) will fix this. if it does not -- consider reporting an issue to that repo.

Might be a one-line fix in our ci setup, so I"m going to mark this as a potential easy hacktoberfest issue. But I don't actually know for sure what needs to be done here.