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

Add automatic NextCloud group for committee chairs

Closes #830

See merge request !1168

Clickable links to Achievements and Societies

Closes #828

See merge request !1160

Fixed Visual Error Committees

Closes #791

See merge request !1149

Fix pizza order where pizza event has no notification, closes #819

Closes #819

See merge request !1163

fix for api assuming non external registration

Closes #822

See merge request !1162

Changed Date Format in List View + Translations

Closes #823

See merge request !1159

Merge branch 'bug/committee-links' of gitlab.science.ru.nl:thalia/concrexit into bug/committee-links

Update pipfile.lock

See merge request !1161

Add membership type to payment notes

See merge request !1147

Fix vars in fstr in conscribosync.py

See merge request !1152