Resolve "Django 3.2 database improvements"

Closes #125

See merge request !150

Bump version to 2.0a5

See merge request !157

Update poetry.lock

See merge request !156

Resolve "PDF export for timetables"

Closes #51

See merge request !77

Resolve "Show print timetable button on mobile devices"

Closes #130

See merge request !154

Denote Teckids e.V. as licensor as defined by EUPL

See merge request !152

This is important to clarify the jurisdiction and court location in case of
license disputes.

Prepare django 3.2 update, update JSONStore migration

See merge request !151

Resolve "Selecting a calendarweek throws error 404"

Closes #108

See merge request !148

Update lockfile

See merge request !149