Recurrence ID must match the DTSTART in any case

[niccokunzmann]

Describe the bug

The Recurrence-ID of an event can have an other format than the dtstart.
But the refined event should be matched. Currently, it is not matched properly as per specification.

9072b26

To Reproduce

Create

• a recurring event
• a recurrence

matrix:

• change the dtstart to date and datetime with different time zones
• change the recurrence-id to date and to datetime with different time zones

Expected behavior

All tests should pass

Additional context

This is partially solved by #35

Suggested implementation

• add an ICS file, example:
  

  python-recurring-ical-events/test/calendars/issue-15-duplicated-events.ics

  Line 1 in f4a90b2

  BEGIN:VCALENDAR

• add a test, example:
  

  python-recurring-ical-events/test/test_issue_15.py

  Line 21 in f4a90b2

  def test_sequence_is_not_present(calendars):

• implement the test
• fix the test

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[niccokunzmann]

probably, this can be solved by converting these recurrence IDs to UTC