Consider adding an .nvmrc file to the repo

https://davidwalsh.name/nvmrc

It could then be used by the setup-node action in the workflows to ensure everywhere the same node.js version is used.

```yaml
- uses: actions/setup-node@v2
with:
node-version-file: '.nvmrc'
```

Start by reviewing the repository workflows that use actions/setup-node and compare how their Node.js versions are currently selected. Add the proposed .nvmrc and update the setup-node configuration to use it consistently, then verify that all affected workflows still resolve the intended version.

Written by the indexing model from the issue text.