Use number literals for booleans in filter conditions.

SQL Server treats literal "false" and "true" as column names. This is probably the same for any other database type that does not have a true "boolean" storage.

Refs: https://github.com/rainlab/blog-plugin/pull/526#issuecomment-716299459

modules/backend/controllers/users/config_filter.yaml

@@ -8,8 +8,8 @@ scopes:
         label: backend::lang.user.superuser
         type: switch
         conditions:
-            - is_superuser = false
-            - is_superuser = true
+            - is_superuser = 0
+            - is_superuser = 1
 
     login_date:
         label: backend::lang.user.last_login