[fix] Fix import formatting to comply with isort/black

Split the long import line into multi-line format to stay within
the 88-character line length limit required by Black and isort.

Author: mn-ram

openwisp_controller/config/base/multitenancy.py

@@ -12,7 +12,10 @@
 
 from .. import settings as app_settings
 from ..exceptions import OrganizationDeviceLimitExceeded
-from ..tasks import bulk_invalidate_config_get_cached_checksum, invalidate_controller_views_cache
+from ..tasks import (
+    bulk_invalidate_config_get_cached_checksum,
+    invalidate_controller_views_cache,
+)
 
 
 class AbstractOrganizationConfigSettings(UUIDModel):