Fix progress demo

components/progress/__tests__/__snapshots__/demo.test.js.snap

@@ -513,7 +513,7 @@ exports[`renders ./components/progress/demo/line.md correctly 1`] = `
         >
           <div
             class="ant-progress-bg"
-            style="width:30%;height:8px;background:red"
+            style="width:30%;height:8px"
           />
         </div>
       </div>

components/progress/demo/line.md

@@ -18,7 +18,7 @@ import { Progress } from 'antd';
 
 ReactDOM.render(
   <div>
-    <Progress percent={30} strokeColor="red" />
+    <Progress percent={30} />
     <Progress percent={50} status="active" />
     <Progress percent={70} status="exception" />
     <Progress percent={100} />