Actually update diffux-core gem
Actually update diffux-core gem

When I bumped the gem version, I failed to commit the Gemfile.lock
changes.

Change-Id: Ib489cebabc78ce2d9fa68832b67821fcfa9256f6

kalw/diffux,diffux/diffux,diffux/diffux,kalw/diffux,kalw/diffux,diffux/diffux