Fix flake8 warnings for tests

tests/__init__.py

tests/api/test_auth.py

tests/api/test_filtering.py

tests/api/test_ratelimiting.py

tests/appservice/test_appservice.py

tests/appservice/test_scheduler.py

tests/crypto/__init__.py

tests/events/test_utils.py

tests/handlers/test_appservice.py

tests/handlers/test_auth.py

tests/handlers/test_profile.py

tests/handlers/test_typing.py

tests/rest/client/v1/__init__.py

tests/rest/client/v1/test_profile.py

tests/rest/client/v1/test_rooms.py

tests/rest/client/v1/test_typing.py

tests/rest/client/v1/utils.py

tests/rest/client/v2_alpha/__init__.py

tests/rest/client/v2_alpha/test_filter.py

tests/rest/client/v2_alpha/test_register.py