Fix #525: bad ISO date RegExp comparison.
Fix #525: bad ISO date RegExp comparison.

jeffbski/joi,thethanghn/react-native-joi,ck-lee/joi,pandeysoni/joi,rmoorman/joi,olistic/joi-extended,cesarmarinhorj/joi,pikselpalette/joi,danielb2/joi,lloydbenson/joi,jagoda/joi,geminiyellow/joi,robertherber/joi-extended,bananaoomarang/joi,opyate/joi,naitsric/joi,tpiecora/joi,davidbenko9/joi