Start using actions/setup-node@v3 due to deprecation warnings

[philrz]

A recent Actions run produced the following warnings during a step that relied on actions/setup-node@v2:

Warning: The `save-state` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

Warning: The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

I can see that actions/setup-node#587 appears to fix this, so if we move to @v3 these should go away.