Add spellchecking check to CI (test PR to see if it fails when typos exist)

[rdimaio]

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[rdimaio]

Works now, but it doesn't automatically pick up the configuration from the config file. There's currently no way to pass this file to the action, so we have 3 options:

1. pass the options from the config file into the GH actions as arguments (downside to this: we need to manually keep the config and the GH action workflow in sync)
2. use pre-commit.ci (probably the most convenient solution, but not sure if we want to rely on an external framework for this)
3. wait for the 'pass configuration' feature to be merged into the GH action. There was a PR from a few years ago but it wasn't merged due to some conflicts. I've picked it up here Add the config file option and tests codespell-project/actions-codespell#80