Fix deprecated package dependency

Great work creating this plugin to help us use Node libs in Stencil. 🎉

But it would be good to update package dependencies from https://www.npmjs.com/package/rollup-plugin-node-polyfills?activeTab=dependencies

```
warning rollup-plugin-node-polyfills > rollup-plugin-inject@3.0.2: This package has been deprecated and is no longer maintained. Please use @rollup/plugin-inject.
```

I checked my `package-lock.json` and found:

```JSON
"rollup-plugin-node-polyfills": {
"version": "0.2.1",
"resolved": "https://registry.npmjs.org/rollup-plugin-node-polyfills/-/rollup-plugin-node-polyfills-0.2.1.tgz",
"integrity": "sha512-4kCrKPTJ6sK4/gLL/U5QzVT8cxJcofO0OU74tnB19F40cmuAKSzH5/siithxlofFEjwvw1YAhPmbvGNA6jEroA==",
"dev": true,
"requires": {
"rollup-plugin-inject": "^3.0.0"
}
},
```

It would be great to change to use ` @rollup/plugin-inject`