refactor(tab): adjust padding in complete mode

src/tabs/index.js

@@ -86,7 +86,7 @@ export default createComponent({
     },
     swipeThreshold: {
       type: [Number, String],
-      default: 4,
+      default: 5,
     },
   },
 

src/tabs/index.less

@@ -57,10 +57,13 @@
 
         &--complete {
           flex: 1 0 auto;
+          padding: 0 @padding-sm;
         }
       }
 
       .van-tabs__nav {
+        padding-right: 8px;
+        padding-left: 8px;
         overflow-x: auto;
         overflow-y: hidden;
         -webkit-overflow-scrolling: touch;