Link data to specific date ranges

The ranges should be directly linked to school terms.

added part::backend type::refactoring workflow::confirmed labels

Decided by the meeting of the maintainers in order to keep data more consistent.

added prio::1 label

changed the description

mentioned in issue AlekSIS-App-Untis#6 (closed)

assigned to @hansegucker

changed the description

created merge request !66 (merged) to address this issue

mentioned in merge request !66 (merged)

closed via commit 75e6e700

mentioned in commit 75e6e700