fix(amis): 修复卡片组件内部插入分栏组件时的渲染异常问题

packages/amis/src/renderers/Card.tsx

@@ -489,7 +489,7 @@ export class CardRenderer extends React.Component<CardProps> {
     if (childNode.type === 'hbox' || childNode.type === 'grid') {
       return render(region, node, {
         key,
-        itemRender: this.itemRender
+        itemRender: this.itemRender.bind(this)
       }) as JSX.Element;
     }