Fixed warning with csv [skip ci]

Author: ankane

Gemfile

@@ -4,10 +4,10 @@ gemspec
 
 gem "rake"
 gem "minitest"
+gem "csv"
 gem "daru"
 gem "matrix" # for daru
 gem "rover-df", platform: [:mri, :x64_mingw]
-gem "csv"
 
 # TODO remove when numo-narray > 0.9.2.1 is released
 if Gem.win_platform?

Rakefile

@@ -3,7 +3,7 @@ require "rake/testtask"
 
 Rake::TestTask.new do |t|
   t.pattern = "test/**/*_test.rb"
-  t.warning = false # for csv and daru
+  t.warning = false # for daru
 end
 
 task default: :test