addYears method
Adds the specified number of years to the current DateTime.
Note: When adding a year to February 29th, it returns February 28th (not March 1st)
Args: years (int): The number of years to add.
Returns: DateTime: A new DateTime object with the added years.
Implementation
DateTime addYears(int years) {
if (years == 0) {
// same
return this;
}
// We used the Jiffy package to add years, months, etc
// https://stackoverflow.com/questions/54792056/add-subtract-months-years-to-date-in-dart
return Jiffy.parseFromDateTime(this).add(years: years).dateTime;
}