Include vendored dependencies

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    ruby_ast_gen (0.4.0)
+    ruby_ast_gen (0.5.0)
 
 GEM
   remote: https://rubygems.org/

ruby_ast_gen.gemspec

@@ -23,12 +23,7 @@ Gem::Specification.new do |spec|
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   gemspec = File.basename(__FILE__)
-  spec.files = IO.popen(%w[git ls-files -z], chdir: __dir__, err: IO::NULL) do |ls|
-    ls.readlines("\x0", chomp: true).reject do |f|
-      (f == gemspec) ||
-        f.start_with?(*%w[bin/ vendor/ test/ spec/ features/ .git .github appveyor Gemfile])
-    end
-  end
+  spec.files = Dir.glob("{lib,exe,sig,vendor}/**/*") + %w[README.md LICENSE.txt Rakefile]
   spec.bindir = "exe"
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]