Exclude isort for Python 3.7

[jesper-friis]

We want tripper to support Python 3.7, but isort only supports Python 3.8+.

If possible, configure pre-commit to ignore isort if Python version < 3.8. An alternative is to run

export SKIP=isort

before running pre-commit for Python 3.7. That is probably the simplest. If you have a virtual environment, you could set (and reset) this in the activate script, so that you don't have to think about it.

If we go that this solution, this issue reduces to documenting that you have to set the SKIP environment variable for Python < 3.8.

[alfredoisg]

Not sure whether it is worth focusing a lot on Python 3.7 given it is reaching its end-of-life this month.
See https://peps.python.org/pep-0537/#lifespan

[sygout]

Ok then Jesper could you confirm and close this issue.