Set package name to Firebase in podspec to match Package.swift

Author: andrewheard

FirebaseVertexAI.podspec

@@ -49,6 +49,10 @@ Firebase SDK.
   s.dependency 'FirebaseCore', '~> 11.7.0'
   s.dependency 'FirebaseCoreExtension', '~> 11.7.0'
 
+  s.pod_target_xcconfig = {
+    'OTHER_SWIFT_FLAGS' => '-package-name Firebase'
+  }
+
   s.test_spec 'unit' do |unit_tests|
     unit_tests_dir = 'FirebaseVertexAI/Tests/Unit/'
     unit_tests.scheme = { :code_coverage => true }