multitenant: inherit from TenantStorageMixin to avoid a warning (#18180)

hobo/multitenant/storage.py

@@ -8,9 +8,15 @@ from django.db import connection
 
 from django.core.files.storage import FileSystemStorage
 
+try:
+    from tenant_schemas.storage import TenantStorageMixin
+except ImportError:
+    class TenantStorageMixin:
+        pass
+
 __all__ = ('TenantFileSystemStorage', )
 
-class TenantFileSystemStorage(FileSystemStorage):
+class TenantFileSystemStorage(FileSystemStorage, TenantStorageMixin):
     '''Lookup files first in $TENANT_BASE/<tenant.schema>/media/ then in default location'''
     def path(self, name):
         if connection.tenant: