tests: move color setting to config

.rspec

@@ -1 +0,0 @@
---color

spec/spec_helper.rb

@@ -14,6 +14,8 @@ RSpec.configure do |config|
   config.mock_with :rspec do |mocks|
     mocks.verify_partial_doubles = true
   end
+  config.tty = true
+  config.color = true
 end
 
 def tmp_dir