fix(firestore, ios): remove nanopb transitive dep from podspec

Upstream firestore-ios-sdk-frameworks issue is fixed and the Firestore binary distribution now directly depends on nanopb as it should, so we should remove the workaround here.

This tangentially fixes compile of InAppMessaging which was specifying a mutually exclusive nanopb version range

packages/firestore/RNFBFirestore.podspec

@@ -39,10 +39,6 @@ Pod::Spec.new do |s|
   # Firebase dependencies
   s.dependency          'Firebase/Firestore', firebase_sdk_version
 
-  # required until firestore-ios-sdk-frameworks is updated, otherwise users of that distribution will have compile failures
-  # see https://github.com/invertase/firestore-ios-sdk-frameworks/issues/59
-  s.dependency          'nanopb', '>= 2.30908.0', '< 2.30910.0'
-
   if defined?($RNFirebaseAsStaticFramework)
     Pod::UI.puts "#{s.name}: Using overridden static_framework value of '#{$RNFirebaseAsStaticFramework}'"
     s.static_framework = $RNFirebaseAsStaticFramework