Bump iOS from 11.0 to 12.4 in Hermes eng podspec (#33939)

Summary:
Deprecate iOS/tvOS SDK 11.0 support now that 12.4+ is required

Context: #33935 (comment)

## Changelog

[iOS] [Fixed] - Deprecate iOS/tvOS SDK 11.0 support now that 12.4+ is required

Pull Request resolved: #33939

Reviewed By: hramos

Differential Revision: D36780553

Pulled By: cortinico

fbshipit-source-id: 64dd12742d1f9f949a89306dd3353ea24a31983d

sdks/hermes-engine/hermes-engine.podspec

@@ -38,7 +38,7 @@ Pod::Spec.new do |spec|
   spec.license     = package["license"]
   spec.author      = "Facebook"
   spec.source      = source
-  spec.platforms   = { :osx => "10.13", :ios => "11.0" }
+  spec.platforms   = { :osx => "10.13", :ios => "12.4" }
 
   spec.preserve_paths      = ["destroot/bin/*"].concat(HermesHelper::BUILD_TYPE == :debug ? ["**/*.{h,c,cpp}"] : [])
   spec.source_files        = "destroot/include/**/*.h"