Update CI matrix and fix tests (resque#766)

* Add Ruby 3.2 to CI matrix

* Copy resque/server/test_helper from Resque

* Tweak matrix

* Ensure that Sinatra > 2.0 is used

For some reason, 1.0 may be installed.
 If 1.0 is used, the following error occurs.
```
<internal:/opt/hostedtoolcache/Ruby/3.2.1/x64/lib/ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require': cannot load such file -- rack/showexceptions (LoadError)
Did you mean?  rack/show_exceptions
```

* Suppress RuboCop offences

.github/workflows/ruby.yml

@@ -26,6 +26,7 @@ jobs:
           - 2.7
           - "3.0"
           - 3.1
+          - 3.2
         resque-version:
           - "master"
           - "~> 2.4.0"
@@ -41,6 +42,8 @@ jobs:
         exclude:
           - ruby-version: head
             rufus-scheduler: 3.2
+          - ruby-version: 3.2
+            rufus-scheduler: 3.2
 
           - ruby-version: 2.3
             resque-version: "~> 1.27"

Gemfile

@@ -24,4 +24,6 @@ else
   gem 'redis', redis_version
 end
 
+gem 'sinatra', '> 2.0'
+
 gemspec

test/resque-web_test.rb

@@ -1,7 +1,7 @@
 # vim:fileencoding=utf-8
 require_relative 'test_helper'
 
-require 'resque/server/test_helper'
+require_relative 'server/test_helper'
 
 context 'on GET to /schedule' do
   setup { get '/schedule' }

test/server/test_helper.rb

@@ -0,0 +1,19 @@
+require 'rack/test'
+require 'resque/server'
+
+module Resque
+  module TestHelper
+    class Test::Unit::TestCase # rubocop:disable Style/ClassAndModuleChildren
+      include Rack::Test::Methods
+      def app
+        Resque::Server.new
+      end
+
+      def self.should_respond_with_success
+        test 'should respond with success' do
+          assert last_response.ok?, last_response.errors
+        end
+      end
+    end
+  end
+end