rrule return incorrect value with freq=MONTHLY

[michaszcz]

Code to reproduce the issue:

from dateutil.rrule import rrule, MONTHLY
import datetime

start = datetime.datetime(2023, 5, 31, 7, 5, 46, tzinfo=datetime.timezone.utc)
end = datetime.datetime(2024, 5, 31, 7, 5, 46, tzinfo=datetime.timezone.utc)  # 1 year difference
result = list(rrule(freq=MONTHLY, dtstart=start, until=end))
len(result)
result

Actual result:

>>> len(result)
8
>>> result
[datetime.datetime(2023, 5, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2023, 7, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2023, 8, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2023, 10, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2023, 12, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2024, 1, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2024, 3, 31, 7, 5, 46, tzinfo=datetime.timezone.utc), datetime.datetime(2024, 5, 31, 7, 5, 46, tzinfo=datetime.timezone.utc)]

Expected result:
The length of the list should be 12, every month should be returned

Environment:
Python 3.9.8
dateutil-version = "2.8.2"