Optional `pre-commit` step requires manual installation of hadolint

[arettig]

Describe the issue

The optional step pre-commit run --all-files fails unless the user has hadolint manually installed (as well as shellcheck, but that is addressed in #1318 ). The hadolint hook in .pre-commit-config.yaml does not actually download the hadolint binary (see hadolint/hadolint#886 ).

What version of this software are you using?

1.7.2.dev0

How can the issue be reproduced?

Following the steps in CONTRIBUTING.md:

pip install pre-commit
pre-commit install -t pre-commit -t pre-push -t commit-msg
pre-commit run --all-files