Please move `eslint` and `eslint-config-airbnb` to devDependencies

[alex-a-pereira]

Running yarn install in my project where I have @iterable/react-native-sdk installed results in yarn complaining about peer dependecies not being met.

devtool dependencies belong in devDependencies which will make yarn not install them in consumers' codebases.

This should be a simple fix!

[alex-a-pereira]

Thanks team, handled in #603