Expo 49 migration

[headwinds]

We're using this awesome library in our project - our user love it!

We want to upgrade to Expo 49 but are stuck - would you consider upgrading to the latest versions of react & react-native and publishing to NPM again? You're only dependencies... ;-D

When I do npm i in my project, I get:

npm ERR! Could not resolve dependency:
npm ERR! peer react@"^16.0.0-beta.5" from react-native-card-flip@1.0.7
npm ERR! node_modules/react-native-card-flip
npm ERR!   react-native-card-flip@"1.0.7" from the root project

[headwinds]

I ended up simply copying CardFlip.js into my project and, since it's modern, I didn't need react-lifecycles-compat so was able to remove line 345 polyfill(CardFlip) and that dependency

It's working perfectly with the latest react & react-native so kudos again for writing such nice code that is standing the test of time!