How can I alter the format of a Date within the title string

I have various files where the title is simply a date, in the following Format: "DD/MM/YYYY". How would I create an action that would update that title by altering the format of that string, so that it would be in the form of: "YYYY-MM-DD"?

Create an action of the type "Replace with regular expression" for th field
Search string: (\d\d)/(\d\d)/(\d\d\d\d)
Replace string: $3-$2-$1