ci: update stale action

[outsideris]

GitHub Actions deprecated Node.js 12 and actions/stale support Node.js 16.

Updating actions/stale to v6 will the deprecation warning.

Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/. Please update the following actions to use Node.js 16: actions/stale

[coveralls]

Coverage remained the same at 94.326% when pulling f564ca2 on outsideris:update-stale-actions into 5f96d51 on mochajs:master.

[juergba]

@outsideris there is still one deprecation warning remaining in your PR test run.
Could you fix this as well, please?
Have you checked the rest of our actions?

[outsideris]

Yes, we use coverallsapp/github-action@master.
However, coverallsapp/github-action doesn't support Node.js 16 yet even upgrading Node.js 16 PR exist.

[outsideris]

I will merge this in a few days.