Sync up the min os versions between the C++ and ObjC CocoaPods support.

Fixes #12944

PiperOrigin-RevId: 537907016

Protobuf-C++.podspec

@@ -25,10 +25,10 @@ Pod::Spec.new do |s|
 
   s.header_mappings_dir = 'src'
 
-  s.ios.deployment_target = '7.0'
+  s.ios.deployment_target = '12.0'
-  s.osx.deployment_target = '10.9'
+  s.osx.deployment_target = '10.13'
-  s.tvos.deployment_target = '9.0'
+  s.tvos.deployment_target = '12.0'
-  s.watchos.deployment_target = '2.0'
+  s.watchos.deployment_target = '6.0'
 
   s.pod_target_xcconfig = {
     # Do not let src/google/protobuf/stubs/time.h override system API