PG作为业务数据库，不支持数组下标更新sql

- [ ] I have searched the [issues](https://github.com/seata/seata/issues) of this repository and believe that this is not a duplicate.

### Ⅰ. Issue Description
PG作为业务数据库，不支持数组下标更新sql

### Ⅱ. Describe what happened

update t_user set money[1]=100.0 where id=1

```
Cause: com.alibaba.druid.sql.parser.ParserException: syntax error, expect EQ, actual LBRACKET
```

### Ⅲ. Describe what you expected to happen

该语句应该合法，提示异常

Start by reproducing the PostgreSQL statement `update t_user set money[1]=100.0 where id=1` and tracing the reported `com.alibaba.druid.sql.parser.ParserException` at the SQL parser. Done means the array-subscript assignment is accepted as valid SQL without the reported syntax error, with regression coverage for this statement.

Written by the indexing model from the issue text.