[renovate]: ignore engines.yarn

[pieh]

Summary

Our current renovate config, result in engines.yarn bumps, which is something we don't want. Not only it would unnecessarily force users to be on latest yarn version, it also make it problematic to run checks on CI (as images used on CircleCI doesn't seem to come with latest yarn version):

Screenshots from #18875

Task

Update https://github.com/gatsbyjs/gatsby/blob/master/renovate.json configuration, so it doesn't try to update engines

[wpanas]

I can take it :)

[pieh]

Nice, go for it @wpanas!

[wpanas]

Can you give me a hint how to test if my changes worked?

[pieh]

Right now I don't have nice solution, but I think creating test repository that would have engines.yarn set in package.json and trying out renovate configuration changes there might be the way to go?

Alternatively if you would find good resource for this, we could just live test changes here directly (as right now we are blocked and can't merge renovate PRs anyway), and we could try force renovate PR refresh

[wpanas]

I used https://docs.renovatebot.com/configuration-options/#ignoredeps to fix it. Either it works or not, but I'm certain that it won't not break anything. It uses exact match, so only yarn is going to be excluded. Other dependencies are going to stay safe and sound.

[sidharthachatterjee]

@wpanas Thanks! Left a comment on your PR