Suppress sass deprecation warning

The following deprecation warning was addressed.

```
Deprecation Warning: Sass's behavior for declarations that appear after nested
rules will be changing to match the behavior specified by CSS in an upcoming
version. To keep the existing behavior, move the declaration above the nested
rule. To opt into the new behavior, wrap the declaration in `& {}`.

More info: https://sass-lang.com/d/mixed-decls

    ╷
5   │ ┌     label {
6   │ │       display: none;
7   │ │     }
    │ └─── nested rule
... │
5   │ ┌     label {
6   │ │       display: none;
7   │ │     }
    │ └─── nested rule
... │
9   │       margin-bottom: 5px;
    │       ^^^^^^^^^^^^^^^^^^ declaration
    ╵
    vendor/bundle/gems/activeadmin_addons-1.10.1/app/assets/stylesheets/activeadmin_addons/inputs/date-ti
me-picker-filter.scss 9:5  @import
(snip)
```

This warning is due to the following change in dart-sass.
sass/dart-sass#2267

app/assets/stylesheets/activeadmin_addons/inputs/date-time-picker-filter.scss

@@ -1,11 +1,10 @@
 .filter_date_time_picker_filter {
   li {
     list-style: none;
+    margin-bottom: 5px;
 
     label {
       display: none;
     }
-
-    margin-bottom: 5px;
   }
 }