use Time::Local qw( timegm_nocheck );

sub get_yesterday {
   my ($date) = @_;
   my ($year, $month, $day) = split(/-/, $date);

   return sprintf("%d-%02d-%02d",
      (gmtime(timegm_nocheck(0, 0, 0, $day-1, month, $year)))[5, 4, 3]
   );
}