TestCase connection_name error

Describe the bug
In tortoise/contrib/test/__init__.py(line:397),there is an error:

    async def _run_outcome(self, outcome, expecting_failure, testMethod) -> None:
        ...
        self.__db__ = Tortoise.get_connection("models") # That's a problem?
        ...

It can be fix to:

class TestCase(TruncationTestCase):
    connection_name:str="models"

    async def _run_outcome(self, outcome, expecting_failure, testMethod) -> None:
        _restore_default()
        self.__db__ = Tortoise.get_connection(self.connection_name)
        if self.__db__.capabilities.supports_transactions:
            connection = self.__db__._in_transaction().connection
            async with TransactionTestContext(connection):
                await super()._run_outcome(outcome, expecting_failure, testMethod)
        else:
            await super()._run_outcome(outcome, expecting_failure, testMethod)

Read tortoise/contrib/test/init.py around line 397 and inspect how TestCase selects its database connection. Make the connection name configurable instead of fixed to "models", then run the relevant test suite and verify TestCase uses the configured connection while preserving transaction handling.