Update the spec URL for field-sizing (#3318)

The `fied-sizing` property has been moved to the CSS Form Control Styling level 1 module.

Author: stof

features/field-sizing.yml

@@ -1,4 +1,4 @@
 name: field-sizing
-spec: https://drafts.csswg.org/css-ui-4/#field-sizing
+spec: https://drafts.csswg.org/css-forms-1/#field-sizing
 description: The `field-sizing` CSS property allows form controls such as `<textarea>` to be sized based on their content.
 group: css