Duplicate runs for every 15 minutes schedule

[CameronNemo]

Schedule of "*/15 * * * *"

These are the results:

2023-07-12 21:55:12,303 WARNING scheduled_task run next_run_time: 2023-07-12 22:00:00.303164 - default_args: {'args': [], 'kwargs': {}}
INFO:     Uvicorn running on http://localhost:8000 (Press CTRL+C to quit)
2023-07-12 22:00:00,304 WARNING scheduled_task run next_run_time: 2023-07-12 22:01:00.304216 - default_args: {'args': [], 'kwargs': {}}
2023-07-12 22:01:00,306 WARNING scheduled_task run next_run_time: 2023-07-12 22:15:00.305922 - default_args: {'args': [], 'kwargs': {}}
2023-07-12 22:15:00,308 WARNING scheduled_task run next_run_time: 2023-07-12 22:16:00.307897 - default_args: {'args': [], 'kwargs': {}}
2023-07-12 22:16:00,309 WARNING scheduled_task run next_run_time: 2023-07-12 22:30:00.309563 - default_args: {'args': [], 'kwargs': {}}

Edit: tested also with every five minute runs. Similar results. I believe I have narrowed down where the issue occurs to this logic: https://github.com/codemation/easyschedule/blob/4023332247ed3645b623b28388d38e13419bf7c4/easyschedule/cron.py#L134-L162