How to disable enter key inside jqueryui datepicker

I am using jQueryUI date picker and when user clicks on a textbox and hits the enter key the current date gets populated. I want to avoid that. I have tried this:

$('#datepicker').on('keypress',  function(e){
    if (e.which == 13) {
        e.preventDefault();
        e.stopPropagation();
        return false; 
    }
});

With no luck

here is the link of demo https://jsfiddle.net/shalini456/zwjzo175/