remove unused imports, improve structure

.pre-commit-config.yaml

calendar_utils/icalevents/icalparser.py

district/blocks.py

district/migrations/0005_auto_20211108_2126.py

district/migrations/0131_migrate_headers.py

district/migrations/0138_auto_20240509_1227.py

district/migrations/0145_auto_20240509_1642.py

district/migrations/0146_auto_20240510_1035.py

district/migrations/0148_auto_20240510_1049.py

district/migrations/0161_auto_20240513_1733.py

district/migrations/0162_add_people_block.py

district/migrations/0163_auto_20240509_1227.py

...migrations/0170_districtpersonpage_after_name_and_more.py

.../migrations/0190_remove_districthomepage_calendar_page.py

district/migrations/0191_delete_districtpersontag.py

...s/0192_remove_districtarticlepage_thumb_image_and_more.py

...3_remove_districthomepage_show_pirati_cz_link_and_more.py

district/models.py

donate/models.py

elections/blocks.py