fix: underlines rendered in wrong color

Cascade text decoration attributes color, thickness and
style in addition to the textdecoration itself.

fixes: #1361

Author: a1rwulf

lib/src/style.dart

@@ -398,6 +398,9 @@ class Style {
         child.textDecoration ?? TextDecoration.none,
         textDecoration ?? TextDecoration.none,
       ]),
+      textDecorationColor: child.textDecorationColor ?? textDecorationColor,
+      textDecorationThickness: child.textDecorationThickness ?? textDecorationThickness,
+      textDecorationStyle: child.textDecorationStyle ?? textDecorationStyle,
       textShadow: child.textShadow ?? textShadow,
       whiteSpace: child.whiteSpace ?? whiteSpace,
       wordSpacing: child.wordSpacing ?? wordSpacing,