Use ISOString for getFormattedDate (#15914)

Use `ISOString`

scripts/release/get-formatted-date.js

@@ -1,8 +1,11 @@
 // TODO: Implement this in `utils.js` when jest.importActual is landed.
 export default function getFormattedDate() {
   const date = new Date();
-  const year = date.getFullYear();
-  const month = String(date.getMonth() + 1).padStart(2, "0");
-  const day = String(date.getDate()).padStart(2, "0");
+  const isoStr = date.toISOString();
+
+  const year = isoStr.slice(0, 4);
+  const month = isoStr.slice(5, 7);
+  const day = isoStr.slice(8, 10);
+
   return { year, month, day };
 }