Move dependency requires to RubyRunner file

Author: pvdb

test/support/ruby_runner.rb

@@ -1,4 +1,8 @@
 # frozen_string_literal: true
+
+require "open3"
+require "fileutils"
+
 module RubyRunner
   include FileUtils
 

test/test_rake_backtrace.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 require File.expand_path("../helper", __FILE__)
-require "open3"
 
 class TestBacktraceSuppression < Rake::TestCase # :nodoc:
   def test_bin_rake_suppressed

test/test_rake_functional.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 require File.expand_path("../helper", __FILE__)
-require "fileutils"
-require "open3"
 
 class TestRakeFunctional < Rake::TestCase # :nodoc:
   include RubyRunner

test/test_rake_reduce_compat.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 require File.expand_path("../helper", __FILE__)
-require "open3"
 
 class TestRakeReduceCompat < Rake::TestCase # :nodoc:
   include RubyRunner