fix(ios): update deployment target

https://github.com/CocoaPods/Specs/blob/master/Specs/2/c/6/GoogleWebRTC/1.1.29400/GoogleWebRTC.podspec.json

Author: CoreyCole

ios/flutter_webrtc.podspec

@@ -17,7 +17,7 @@ A new flutter plugin project.
   s.dependency 'Flutter'
   s.dependency 'libyuv-iOS'
   s.dependency 'GoogleWebRTC', '1.1.29400'
-  s.ios.deployment_target = '9.0'
+  s.ios.deployment_target = '10.0'
   s.static_framework = true
 end