Upgrade to node 16

[brettcannon]

The node 12 runner is being deprecated.

[brettcannon]

Will require updating (at least):

1. https://github.com/brettcannon/check-for-changed-files/blob/main/tsconfig.json
2. https://github.com/brettcannon/check-for-changed-files/blob/main/action.yml
3. https://github.com/brettcannon/check-for-changed-files/blob/main/package.json
4. https://github.com/brettcannon/check-for-changed-files/blob/main/.github/workflows/pull-request.yml

[lukasoppermann]

Hey is there any progress on this? I am also getting the warning when using this action and would like to get it resolved. :D

[brettcannon]

@lukasoppermann no progress at the moment. If you want to send a PR that would be great, otherwise I do plan to eventually get to this.

[brettcannon]

https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions#runsusing-for-javascript-actions to document that fact that there isn't a way to skip to Node 18.