fix deprecated invocation of keyboardShouldPersistTaps

[LaneRamp]

see https://facebook.github.io/react-native/docs/scrollview.html

[LaneRamp]

@d-a-n this should be a quick one, hope you have time to get to it (i hate warnings)

[mikaello]

I think you are better of switching to a maintained fork, e.g. react-native-modal-selector than waiting for @d-a-n to merge this.