mysql JSONSet Build bool type to 1/0，expected true/false

## GORM Playground Link

https://github.com/go-gorm/datatypes/pull/284





问题描述
```golang
	set := datatypes.JSONSet("object")
	set.Set("test_bool", meta.TestBool)
       db.....Update("object", set)

```

执行后结果

```
 { "test_bool": 1}

```

修改
bool 类型直接构造为 SQL，而不是通过 statement AddVar 替换为占位符