Upgrades for Wagtail 4.1

district/templates/district/base.html

districts/templates/districts/base.html

donate/models.py

donate/templates/donate/base.html

elections2021/models.py

green_deal/templates/green_deal/base.html

main/templates/main/base.html

senat_campaign/models.py

senate/templates/senate/base.html

tuning/static/majak/css/tuning.css

uniweb/templates/uniweb/base.html