Fix MR suggestions from Zulip

...rations/0115_alter_districtcustompage_content_and_more.py

district/models.py

majak/urls.py

shared/blocks.py

shared/models.py

shared/static/shared/js/vue-formulate-helper.js

...emplates/shared/blocks/newsletter_subscription_block.html

shared/templatetags/shared_filters.py

shared/utils.py

...rations/0044_alter_uniwebflexiblepage_content_and_more.py

uniweb/models.py