docs(components): [cascader] fix type error (#10961)

closed #10937

docs/examples/cascader/basic.vue

@@ -20,7 +20,7 @@ import { ref } from 'vue'
 const value = ref([])
 
 const props = {
-  expandTrigger: 'hover',
+  expandTrigger: 'hover' as const,
 }
 
 const handleChange = (value) => {

docs/examples/cascader/dynamic-loading.vue

@@ -3,8 +3,10 @@
 </template>
 
 <script lang="ts" setup>
+import type { CascaderProps } from 'element-plus'
+
 let id = 0
-const props = {
+const props: CascaderProps = {
   lazy: true,
   lazyLoad(node, resolve) {
     const { level } = node