fix: Move .podspec to root (#376)

* Move .podspec to root

* Update .podspec source_files location

ios/RNDeviceInfo.podspec → RNDeviceInfo.podspec

@@ -12,6 +12,6 @@ Pod::Spec.new do |s|
 
   s.source       = { :git => "https://github.com/rebeccahughes/react-native-device-info.git" }
 
-  s.source_files  = "RNDeviceInfo/*.{h,m}"
+  s.source_files  = "ios/RNDeviceInfo/*.{h,m}"
 
 end