fix(spark_css): format css_outline.dart

This commit fixes the formatting of `css_outline.dart` to comply with the CI requirements.
The previous commit failed the format check. This commit runs `dart format` on the file.

Author: kevin-sakemaer

packages/spark_css/lib/src/css_types/css_outline.dart

@@ -42,11 +42,7 @@ final class _CssOutlineShorthand extends CssOutline {
   final CssBorderStyle? style;
   final CssColor? color;
 
-  const _CssOutlineShorthand({
-    this.width,
-    this.style,
-    this.color,
-  }) : super._();
+  const _CssOutlineShorthand({this.width, this.style, this.color}) : super._();
 
   @override
   String toCss() {