End date of recurring events incorrectly set to initial ocurrence in events API

[timobrembeck]

Describe the Bug

The end date of recurring events is incorrectly set to the end date of the initial occurrence of the event in the API response.

Steps to Reproduce

1. Retrieve events API http://localhost:8000/api/augsburg/de/events/
2. See incorrect date

Expected Behavior

The end date should contain the end date of the specific occurrence

Actual Behavior

The end date of the initial even is used

Additional Information

This bug was introduced with commit 4465f01 and is also reflected in our current test data:

integreat-cms/tests/api/expected-outputs/augsburg_de_events.json

Lines 96 to 101 in 718a911

	"start": "2030-01-03T13:00:00+01:00",
	"start_date": "2030-01-03",
	"start_time": "13:00:00",
	"end": "2030-01-01T15:00:00+01:00",
	"end_date": "2030-01-01",
	"end_time": "15:00:00",