Tweak linter override to fix build

As of stylelint v14.11.0, the `stylelint-disable-line` override
no longer appears to work in this case, giving a build failure of

```
61:3 Unexpected qualifying type selector "a.ui-state-default" selector-no-qualifying-type
```

I suspect this is down to this change: stylelint/stylelint#6260

Applying the ignore to the block of CSS rather than to the line
seems to appease the linter.

app/assets/stylesheets/calendar.scss

@@ -57,14 +57,16 @@ $datepicker-border-shadown-color: rgba(0, 0, 0, .1);
     color: inherit;
   }
 
+  /* stylelint-disable selector-no-qualifying-type */
   .ui-state-active,
-  a.ui-state-default:hover { // stylelint-disable-line selector-no-qualifying-type
+  a.ui-state-default:hover {
     border: 2px solid $gray;
     padding: 9px 4px;
     text-decoration: none;
     color: $gray;
     font-weight: bold;
   }
+  /* stylelint-enable selector-no-qualifying-type */
 
   .ui-datepicker-today .ui-state-default {
     border: 2px solid $turquoise;