Prettier config causes lint

The default .prettierrc.js generated by gts itself causes a lint issue triggered by the gts lint config:

Rest/spread properties are not supported until Node.js 8.3.0. The configured version range is '>=8.0.0'.eslint[n/no-unsupported-features/es-syntax](https://github.com/weiran-zsd/eslint-plugin-node/blob/HEAD/docs/rules/no-unsupported-features/es-syntax.md)

That's a pretty old version of Node to be limited to. I'm not sure where the config is inherited from but I worked around it with:

```json
{
"n/no-unsupported-features/es-syntax": [
"error",
{
"version": ">=20.0.0",
"ignores": []
}
]
}
```