Fixed gemspec date format.
Fixed gemspec date format.

sancopanco/koala,christer155/koala,lucaskds/koala,adparlor/koala,lisa-lina/koala,chrisortman/koala,arsduo/koala,Loke155/koala,hendricius/koala,mateusrevoredo/koala,supriyantomaftuh/koala,sideci-sample/sideci-sample-koala,samnang/koala,morgoth/koala