Use `.nvmrc` file to declare the `node` version to use

[kinggoesgaming]

This will make it so we don't need to change the version 6 times (1 time in package.json, 1 in other/Dockerfile and 4 times in .github/workflows/deploy.yml. Instead it will be only 3 times.

Also anyone using nvm to manage node version can use nvm use to match version used with the stack for eliminating issues that can raise due to differing node versions (These should be rare, but still a possibility.)

[kinggoesgaming]

closing this... as using package.json was decided in #801