bump iOS and tvOS from 11.0 to 12.4 in cocoapods

Summary:
Changelog: [iOS][Deprecated] Deprecating support for iOS/tvOS SDK 11.0, 12.4+ is now required

allow-large-files

Reviewed By: sammy-SC

Differential Revision: D34547333

fbshipit-source-id: a24bb09d03939a092de4198efb1aa4a44c69f718

ReactCommon/cxxreact/React-cxxreact.podspec

@@ -28,7 +28,7 @@ Pod::Spec.new do |s|
   s.homepage               = "https://reactnative.dev/"
   s.license                = package["license"]
   s.author                 = "Facebook, Inc. and its affiliates"
-  s.platforms              = { :ios => "11.0", :tvos => "11.0" }
+  s.platforms              = { :ios => "12.4", :tvos => "12.4" }
   s.source                 = source
   s.source_files           = "*.{cpp,h}"
   s.exclude_files          = "SampleCxxModule.*"