don't presume pre-commit-config exists in ensure_renv_compat

[mpadge]

@lorenzwalthert Easy to reproduce the 🐛 behind this one:

1. Go to a directory anywhere that is not an R package and/or does not have a pre-commit-config.yaml file
2. Start R
3. type library(precommit) and watch it error

---

Another question for you here, before i open a hopefully unnecessary issue: I have entirely broken precommit (this package, not the python one) by manually removing all cached renv directories, and removing ~/.cache/R/R.cache. precommit now fails to find any renv-ed versions of desc, styler, docopt, whatever. I've tried removing and reinstalling everything, but no matter what I do precommit fails to reestablish its renv. Any quick tips? Or shall i open an issue?

[lorenzwalthert]

Great, thanks for the contribution.

[lorenzwalthert]

Can you add a news bullet according to tidyverse style?

[lorenzwalthert]

As per the other problem: This is probably a pre-commit issue. Can you run $ pre-commit clean to clean the pre-commit cache?

[mpadge]

As per the other problem: This is probably a pre-commit issue. Can you run $ pre-commit clean to clean the pre-commit cache?

Yep, that did it. Thanks! I've added news item too

[lorenzwalthert]

Thanks @mpadge 🥳