add original spec files code back

Author: jcat4

model_context_protocol.gemspec

@@ -19,7 +19,9 @@ Gem::Specification.new do |spec|
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage
 
-  spec.files = Dir.glob("lib/**/*.rb").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  spec.files = Dir.chdir(File.expand_path("..", __FILE__)) do
+    %x(git ls-files -z).split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
 
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }