fix: underline of colored links is in the wrong color

If you have a link with a color style, the expectation is that the
underline of the link is the same color, hence we need to implicitly
set the text decoration color as well, when we apply the text color.

Author: a1rwulf

lib/src/css_parser.dart

@@ -292,7 +292,7 @@ Style declarationsToStyle(Map<String, List<css.Expression>> declarations) {
           style.border = newBorder;
           break;
         case 'color':
-          style.color =
+          style.color = style.textDecorationColor =
               ExpressionMapping.expressionToColor(value.first) ?? style.color;
           break;
         case 'direction':