Test the merchandise package

See merge request !1190

Data minimisation

See merge request !1185

Add automatic testing for model str method

See merge request !1186

This adds dynamic tests which check if the overwritten __str__ method of
a Model is not the same as the default __str__ method

Do not specifiy parameters for coverage in ci: use .coveragerc

See merge request !1187

Replace Google Drive with Nextcloud links in styleguide

See merge request !1184

Restrict changing registration to users with change registration perms

Closes #825

See merge request !1166

Thumbnail the merchandise images

See merge request !1178

Replace the wiki menu item by Nextcloud

See merge request !1177

Fix member tabs active state

See merge request !1181

Improve createfixtures

Closes #827

See merge request !1182

Allow board membership to contain end date

Closes #416

See merge request !1183

Migrate to poetry and remove tox

Closes #829

See merge request !1176

Do migrate, collectstatic and compress in entrypoints

Closes #831

See merge request !1179

Remove redundant CMD instruction from Dockerfile

See merge request !1180

The instruction does nothing for the production entrypoint, because it
runs an uwsgi server.
The instruction is redundant for the default entrypoint, because --help
is implied if no command is given to manage.py.

Fix admin.py headers in payments

See merge request !1175

Change generate thumbnail url

See merge request !1173

Change sendfile url

See merge request !1171

Fix events payments migration

See merge request !1172

Always show member group members for authenticated users

Closes #478

See merge request !1165

Remove duplicate code from photos_cards.py

See merge request !1167

Fix NoneType error in payments csv export

See merge request !1169