Enforcement of correct NVM/NPM version

I recently ran into an issue whereby `.gitignore` files were not being included in the tar.gz. This was due to the fact that I was using npm v9 instead of v6.

We should enforce/validate that the user is running the required version of nvm/npm before packaging to ensure correct bundling.

A potentials solution could be to add an engines entry into the root package.json specifying npm v6 i.e:

```

{
"engines": {
"npm": "^6"
}
}
```

Start with the root package.json and trace how packaging is invoked. Check how the project currently handles npm or nvm version requirements and whether the proposed npm ^6 constraint is enforced before creating the tar.gz. Done means unsupported versions are identified before packaging and .gitignore files are included.

Written by the indexing model from the issue text.