fix: 计算属性参数优化

package.json

 {
   "name": "panda-xform",
-  "version": "5.7.7",
-  "description": "5.7.7 计算规则优化",
+  "version": "5.7.8",
+  "description": "5.7.8 计算属性参数优化",
   "keywords": [
     "panda-xform"
   ],

src/core/FormRender/watch.js

@@ -32,7 +32,7 @@ const jsonToValues = (data, paths) => {
   if (Array.isArray(paths)) {
     paths.forEach(v => {
       let fieldName = v.path.split('.')[1]
-      let fieldValue = '0'
+      let fieldValue = ''
       let item = formValue.find(s => s.fieldName === fieldName)
       if (item) {
         fieldValue = item.fieldValue