fix: billClass class应为number

modules/all_models/bill_class.js

@@ -8,7 +8,7 @@ const billClass = new Schema({
     name: String,
     code: String,
     itemCharacter: String,
-    class: { type: String, index: true }, // 分类
+    class: { type: Number, index: true }, // 分类
     classCode: { type: String, index: true }, // 类别别名
 }, {versionKey: false});