pre-commit hooks are broken on Windows

[mdboom]

Running pre-commit run --all-files on a clean checkout on Windows fails in a number of ways.

This prevents developers on Windows (non-WSL) from effectively working on this codebase.

We should fix any bugs in the pre-commit checks, and then add a job to CI to run pre-commit run --all-files on Windows (or add a config option for pre-commits built-in CI to get it to run on Windows as well, if that's possible).