fix(singleAxis): fix line width in singleAxis (#9965)

src/chart/sankey/SankeySeries.js

@@ -145,7 +145,7 @@ var SankeySeries = SeriesModel.extend({
 
         levels: [],
 
-        // Value can be 'left', 'right'
+        // Value can be 'left' or 'right'
         nodeAlign: 'justify',
 
         itemStyle: {

src/coord/single/AxisModel.js

@@ -63,7 +63,7 @@ var defaultOption = {
     axisLine: {
         show: true,
         lineStyle: {
-            width: 2,
+            width: 1,
             type: 'solid'
         }
     },
@@ -79,7 +79,7 @@ var defaultOption = {
         show: true,
         length: 6,
         lineStyle: {
-            width: 2
+            width: 1
         }
     },