(maint) Removing 'pending' for bundle management acceptance

The pending test for bundle management fails on appveyor because it
actually passes due to the presence of devkit.
This test should not be pending - there should be a devkit installed.
The test can be manually ignored on workstations that don't/can't have
devkit.

spec/acceptance/bundle_management_spec.rb

@@ -15,7 +15,7 @@
       its(:stderr) { is_expected.to match(%r{Checking for missing Gemfile dependencies}i) }
 
       describe file('Gemfile.lock') do
-        it { pending 'json install requires ruby devkit' if Gem.win_platform?; is_expected.to be_file }
+        it { is_expected.to be_file }
       end
     end
   end