Fix HashWithIndifferentAccess#without bug

[abraham-chan]

Summary

Inconsistent behavior when calling without on a HashWithIndifferentAccess e.g.

{a: 1}.with_indifferent_access.without("a")
# {}
{a: 1}.with_indifferent_access.without(:a)
# {"a"=>1} 
# Expected {}

# But except works
{a: 1}.with_indifferent_access.except("a")
# {}
{a: 1}.with_indifferent_access.except(:a)
# {}

Other Information

I'm not sure if the approach I took was the correct one, but except behaves correctly and appears to do the exact same thing, as far as I can tell.

[rails-bot]

Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @kaspth (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

This repository is being automatically checked for code quality issues using Code Climate. You can see results for this analysis in the PR status below. Newly introduced issues should be fixed before a Pull Request is considered ready to review.

Please see the contribution instructions for more information.