Change The Date Format In A Collection Column

Input collection: myBirthdays20

Person	Birthday
Denis	11/03/1987
Rebecca	02/01/1978
Audrie	21/11/1992
Nathan	15/05/1995
Jared	27/09/1956

Output collection: mySolution20

Person	Birthday
Denis	1987-03-11
Rebecca	1978-01-02
Audrie	1992-11-21
Nathan	1995-05-15
Jared	1956-09-27

Solution code:

//Create a collection
ClearCollect(myBirthdays20,
{Person: "Denis", Birthday: Text(Date(1987,03,11),"[$-en-US]dd/mm/yyyy")},
{Person: "Rebecca", Birthday: Text(Date(1978,01,02),"[$-en-US]dd/mm/yyyy")},
{Person: "Audrie", Birthday: Text(Date(1992,11,21),"[$-en-US]dd/mm/yyyy")},
{Person: "Nathan", Birthday: Text(Date(1995,05,15),"[$-en-US]dd/mm/yyyy")},
{Person: "Jared", Birthday: Text(Date(1956,09,27),"[$-en-US]dd/mm/yyyy")}
);

//Reformat the dates in a column code
ClearCollect(mySolution20,myBirthdays20);
UpdateIf(
    mySolution20,
    true,
    {Birthday: Text(DateValue(Birthday,"en-US"),"[$-en-US]yyyy-mm-dd")}
);