Make dependency on Makefile more accurate

Author: KitaitiMakoto

bindings/ruby/Rakefile

@@ -38,7 +38,7 @@ LIB_NAME = "whisper".ext(RbConfig::CONFIG["DLEXT"])
 SO_FILE = File.join("ext", LIB_NAME)
 LIB_FILE = File.join("lib", LIB_NAME)
 
-file "ext/Makefile" => ["ext/extconf.rb"] + SOURCES do |t|
+file "ext/Makefile" => ["ext/extconf.rb", "ext/ruby_whisper.h", "ext/ruby_whisper.cpp"] + SOURCES do |t|
   Dir.chdir "ext" do
     ruby "extconf.rb"
   end