fix(appcheck): workaround iOS build issue when targetting platforms <…

… iOS 11

The `FirebaseAppCheck` podspec itself supports >= 9.0, however the subspec defined in `Firebase` podspec has it marked as >= 11.0 - so we'll directly depend on `FirebaseAppCheck` instead for now.

packages/firebase_app_check/firebase_app_check/ios/firebase_app_check.podspec

@@ -34,7 +34,9 @@ Pod::Spec.new do |s|
   # Firebase dependencies
   s.dependency 'firebase_core'
   s.dependency 'Firebase/CoreOnly', "~> #{firebase_sdk_version}"
-  s.dependency 'Firebase/AppCheck', "~> #{firebase_sdk_version}"
+  # TODO(salakar): Directly depend on AppCheck podspec to avoid issues with subspec:
+  # https://github.com/firebase/firebase-ios-sdk/pull/9187 (pending acceptance & merge)
+  s.dependency 'FirebaseAppCheck', "~> #{firebase_sdk_version}-beta"
 
   s.static_framework = true
   s.pod_target_xcconfig = {