Adopt pre-commit hook for the `codespell` tool

[davidorme]

          Btw there is a pre-commit hook for the `codespell` tool that can be useful for typos like this. We use it in the [`python-template` repo](https://github.com/ImperialCollegeLondon/python-template/).

Originally posted by @alexdewar in #845 (comment)