不支持选择指定的事务管理器。

Spring的 `@Transactional` 当在配置文件中有多个 TransactionManager , 可以用该属性`transactionManager` 指定选择哪个事务管理器。而目前 `@TxTransaction` 还不支持指定某个事务管理器。我这边提个pr，你看看

Start by tracing how @TxTransaction resolves the transaction manager and compare it with Spring's @Transactional transactionManager attribute. Identify the annotation and configuration entry points involved, then verify that a named manager can be selected when multiple managers are configured.

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