fix: avatar outline syntax style (#934)

packages/semi-foundation/avatar/variables.scss

@@ -45,4 +45,4 @@ $spacing-avatar_extra_small-marginLeft: -10px; // 头像左侧外边距 - 超小
 $width-avatar_extra_extra_small-border: 1px; // 头像描边尺寸 - 极小
 $spacing-avatar_extra_extra_small-marginLeft: -4px; // 头像左侧外边距 - 极小
 
-$width-avatar-outline: 2px //头像聚焦轮廓宽度
+$width-avatar-outline: 2px; //头像聚焦轮廓宽度