fix: skipped run after daylight saving turnover point (#154)

[CipherdevNL]

Fixed the skipping runs that are on the daylight saving days as reported in #154 and #202. These examples are also included in a unit test.

As of my understanding, this issue occurs only when a fixed hour is set after the turnover point of 02:00. The issue lies in the timezoneSafeModify function, which converts the datetime into UTC and back towards the original timezone. When going back, PHP is so "kind" of applying the daylight saving time, resulting in one additional hour than expected.

This eventually comes back into the getRunDate, which decides that the time doesn't satisfy the expected hour, as it got moved over by 1 hour. This makes it skip the daylight saving day completely.

As a solution I've implemented an compensation check that will subtract one hour when DST has started, this to make sure the "target" value is actual being met.

[thewunder]

I checked out your branch, but

$schedule = new CronExpression('0 10 * * *');
$runs = $schedule->getMultipleRunDates(3, '2025-03-08 09:00:00', timeZone: 'America/Chicago');

Is still skipping the 9th...

EDIT: Woops I didn't have your fix branch checked out... IT WORKS @dragonmantank merge and release please!