refactor: 汇率国家查询时限定5个

src/views/ecw/currencyRate/query.vue

@@ -11,7 +11,7 @@
       </el-select>
     </el-form-item>
     <el-form-item :label="$t('国家')" prop="countries">
-      <el-select v-model="params.countries" filterable multiple :placeholder="$t('请选择国家')" clearable>
+      <el-select v-model="params.countries" filterable multiple :multiple-limit="5" :placeholder="$t('请选择国家')" clearable>
         <el-option v-for="item in countries" :key="item.id" :label="$l(item, 'name')" :value="item.id"/>
       </el-select>
     </el-form-item>