Add lib folder to the list of published files in package

[haikov]

Hey, awesome work on the module, thank you!

This small PR addresses #1.

Currently published npm package doesn't include the lib/ folder, as you can see here https://www.npmjs.com/package/@wilmxre/react-native-mesh-gradient?activeTab=code, which makes the package unusable after installation.

This is caused by lib/ folder missing from the list of files in package.json. I'm not sure at which point it dissapeared, since the template should've initially had it (see https://github.com/callstack/react-native-builder-bob/blob/main/packages/create-react-native-library/templates/common/%24package.json#L22).

[farzd]

@wilmxre Do everyone a favour and take this off the npm registry, you're wasting everyones time with a broken package. @haikov even created a PR but you've been too lazy to accept and merge it in.