next_occurrences can return incorrect times when `from` time is near DST boundary.

[flivni]

It seems like there is a bug where if you pass a from time to schedule.next_occurrences that is close to the DST boundary, you can get future occurrences that occur on the wrong time.

E.g. A recurring appointment that occurs every Sunday at 01:15 am London time. If you call schedule.next_occurrences(from_time) where from_time is just prior to March 27, 2022 01:00 am, all occurrences shift an hour forward to 2:15 am local time.

I created a PR with a failing test that demonstrates the issue.
#524

Any help would be appreciated!