[BB-4548] Unify sprint start/end dates
The following pieces of code are using the native Jira sprint start/end dates instead of the higher-level API:
- https://gitlab.com/opencraft/dev/sprints/-/blob/b4907ad8b2a4641d169494f5c0d00c8302215bc2/sprints/dashboard/utils.py#L516
- https://gitlab.com/opencraft/dev/sprints/-/blob/b4907ad8b2a4641d169494f5c0d00c8302215bc2/sprints/dashboard/utils.py#L500
- https://gitlab.com/opencraft/dev/sprints/-/blob/b4907ad8b2a4641d169494f5c0d00c8302215bc2/sprints/dashboard/tasks.py#L275-276
PR: https://github.com/open-craft/sprints/pull/81
Update: we had to revert this feature in !5 (merged). !7 (merged) reapplies it and fixes the issue. Jira ticket: BB-4767.
Edited by Piotr Surowiec