[Release] Bump spec to 9.4.0 and add changelog entry (#116)

CHANGELOG.md

@@ -1,3 +1,6 @@
+# v9.4.0
+- Add privacy manifest. (#114)
+
 # v9.3.0
 - Added new APIs for attaching product ID data to an event.
 - Fix `0x8BADF00D` crashes and add diagnostics. ([firebase-ios-sdk/#9859](https://github.com/firebase/firebase-ios-sdk/issues/9859))

GoogleDataTransport.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'GoogleDataTransport'
-  s.version          = '9.3.0'
+  s.version          = '9.4.0'
   s.summary          = 'Google iOS SDK data transport.'
 
   s.description      = <<-DESC