Add Gemfile to test with Rails 7.0 and fix the test for it

.gitignore

@@ -46,3 +46,4 @@ coverage/*
 .tool-versions
 
 spec/gemfiles/*.lock
+.byebug_history

spec/gemfiles/Gemfile.rails-7.0

@@ -0,0 +1,14 @@
+source "http://rubygems.org"
+
+gemspec path: '../../'
+
+gem 'rails', "~> 7.0.0"
+gem 'responders', '~> 3.0'
+gem 'sqlite3'
+gem 'sprockets', '~> 3.0'
+gem "jquery-rails"
+gem "thin"
+gem 'capybara', '~> 2.1'
+gem 'acts_as_caxlsx', git: 'https://github.com/caxlsx/acts_as_caxlsx.git'
+
+gem 'byebug'

spec/rails_app/app/controllers/users_controller.rb

@@ -19,7 +19,11 @@ def index
   def show
     @user = User.find(params[:id])
     respond_with(@user) do |format|
-      format.xlsx { render "respond_with.xlsx.axlsx" }
+      if Gem::Version.new("7.0") <= Rails.gem_version
+        format.xlsx { render "respond_with" }
+      else
+        format.xlsx { render "respond_with.xlsx.axlsx" }
+      end
     end
   end