refactor: have testing.rb require rspec.rb

This eliminates the conditional check for RSpecHelpers and simplifies
client usage - they only need to require code_teams/testing.

Author: joemsak

README.md

@@ -116,7 +116,7 @@ end
 `code_teams` provides test helpers for creating temporary teams in your specs without writing YML files to disk. Add the following to your `spec_helper.rb` (or `rails_helper.rb`):
 
 ```ruby
-require 'code_teams/rspec'
+require 'code_teams/testing'
 
 CodeTeams::Testing.enable!
 ```

lib/code_teams/testing.rb

@@ -4,6 +4,7 @@
 
 require 'securerandom'
 require 'code_teams'
+require 'code_teams/rspec'
 
 module CodeTeams
   # Utilities for tests that need a controlled set of teams without writing YML
@@ -26,7 +27,7 @@ def self.enable!
       return unless defined?(RSpec)
 
       T.unsafe(RSpec).configure do |config|
-        config.include CodeTeams::RSpecHelpers if defined?(CodeTeams::RSpecHelpers)
+        config.include CodeTeams::RSpecHelpers
 
         config.around do |example|
           example.run

spec/lib/code_teams/r_spec_helpers_integration_spec.rb

@@ -1,4 +1,4 @@
-require 'code_teams/rspec'
+require 'code_teams/testing'
 
 CodeTeams::Testing.enable!