adhocracy-plus/templates: fix outdated phone number, fix redirects to

[goapunk]

root instead of hardcoded value

• fix template lint errors and reformat

fixes https://github.com/liqd/a4-defakts/issues/46

Tasks

• [ ] PR name contains story or task reference
• [ ] Documentation (docs and inline)
• [ ] Tests (including n+1 and django_assert_num_queries where applicable)
• [x] Changelog