[iOS] Add React dependency to Podspec
[iOS] Add React dependency to Podspec

Support older versions of Swift by allowing `use_frameworks!` in CocoaPods
bsudekum/react-native-mapbox-gl,bsudekum/react-native-mapbox-gl,bsudekum/react-native-mapbox-gl,bsudekum/react-native-mapbox-gl