Update CI configuration and gemspec

Author: byroot

.github/workflows/test.yml

@@ -11,5 +11,6 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
+          bundler-cache: true
           ruby-version: ${{ matrix.ruby }}
-      - run: rake
+      - run: bundle exec rake

Gemfile

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+# Specify your gem's dependencies in heap-profiler.gemspec
+gemspec
+
+gem "rake"
+gem "minitest"

Gemfile.lock

@@ -0,0 +1,22 @@
+PATH
+  remote: .
+  specs:
+    builder (3.2.4)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    minitest (5.23.1)
+    rake (13.2.1)
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+  builder!
+  minitest
+  rake
+
+BUNDLED WITH
+   2.3.27

builder.gemspec

@@ -1,22 +1,12 @@
 # frozen_string_literal: true
 require './lib/builder/version'
 
-PKG_VERSION = Builder::VERSION
-
-PKG_FILES = Dir[
-  '[A-Z]*',
-  'doc/**/*',
-  'lib/**/*.rb',
-  'test/**/*.rb',
-  'rakelib/**/*'
-]
-
 Gem::Specification.new do |s|
 
   #### Basic information.
 
   s.name = 'builder'
-  s.version = PKG_VERSION
+  s.version = Builder::VERSION
   s.summary = "Builders for MarkUp."
   s.description = %{\
 Builder provides a number of builder objects that make creating structured data
@@ -26,12 +16,19 @@ simple to do.  Currently the following builder objects are supported:
 * XML Events
 }
 
-  s.files = PKG_FILES
+  pkg_files = Dir[
+    '[A-Z]*',
+    'doc/**/*',
+    'lib/**/*.rb',
+    'test/**/*.rb',
+    'rakelib/**/*'
+  ]
+
+  s.files = pkg_files
   s.require_path = 'lib'
 
-  s.test_files = PKG_FILES.select { |fn| fn =~ /^test\/test/ }
+  s.test_files = pkg_files.select { |fn| fn =~ /^test\/test/ }
 
-  s.has_rdoc = true
   # s.extra_rdoc_files = rd.rdoc_files.reject { |fn| fn =~ /\.rb$/ }.to_a
   s.rdoc_options <<
     '--title' <<  'Builder -- Easy XML Building' <<