ruby : specify Apple frameworks explicitly on build (#3270)

* Add Apple frameworks to $LDFLAGS when needed

* Add utility method to Options

* Remove unnecessary propaty date from gemspec

* Add Apple frameworks for CoreML build

* Add Accelerate framework only for Apple platform

* Fix ZipURI#cache signature

* Download test fixtures if needed

bindings/ruby/sig/whisper.rbs

@@ -412,7 +412,7 @@ module Whisper
     end
 
     class ZipURI < URI
-      def cache: () -> String
+      def cache: () -> Pathname
       def clear_cache: () -> void
     end
   end