[Release] Update versions for Release 10.21.0 (#12288)

FirebaseAnalyticsOnDeviceConversion.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
     s.name             = 'FirebaseAnalyticsOnDeviceConversion'
-    s.version          = '10.20.0'
+    s.version          = '10.21.0'
     s.summary          = 'On device conversion measurement plugin for FirebaseAnalytics. Not intended for direct use.'
 
     s.description      = <<-DESC
@@ -18,7 +18,7 @@ Pod::Spec.new do |s|
 
     s.cocoapods_version = '>= 1.10.2'
 
-    s.dependency 'GoogleAppMeasurementOnDeviceConversion', '10.20.0'
+    s.dependency 'GoogleAppMeasurementOnDeviceConversion', '10.21.0'
 
     s.static_framework = true