Unit Test Failure: GaussDBSyntaxError due to syntax error at or near "$1" in `test_void `

[setoru]

Description:
When running the test case tests/test_codecs.py::TestCodecs::test_void, a GaussDBSyntaxError occurs due to a syntax error at or near "$1".

Logs:

Traceback (most recent call last):
  File "/usr/lib64/python3.9/unittest/case.py", line 59, in testPartExecutor
    yield
  File "/usr/lib64/python3.9/unittest/case.py", line 592, in run
    self._callTestMethod(testMethod)
  File "/usr/lib64/python3.9/unittest/case.py", line 550, in _callTestMethod
    method()
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/_testbase/__init__.py", line 92, in wrapper
    self.loop.run_until_complete(coro)
  File "/usr/lib64/python3.9/asyncio/base_events.py", line 642, in run_until_complete
    return future.result()
  File "/home/gaussdbuser/gaussdb-python-async/tests/test_codecs.py", line 571, in test_void
    await self.conn.fetchval('select now($1::void)', '')
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/connection.py", line 715, in fetchval
    data = await self._execute(query, args, 1, timeout)
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/connection.py", line 1865, in _execute
    result, _ = await self._execute(
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/connection.py", line 1962, in _execute
    result = await self._do_execute(
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/connection.py", line 2005, in _do_execute
    stmt = await self._get_statement(
  File "/home/gaussdbuser/gaussdb-python-async/venv/lib64/python3.9/site-packages/async_gaussdb/connection.py", line 439, in _get_statement
    statement = await self.protocol.prepare(
  File "async_gaussdb/protocol/protocol.pyx", line 165, in prepare
    return await waiter
async_gaussdb.exceptions.GaussDBSyntaxError: syntax error at or near "$1"

How to reproduce it:

pytest --durations=0 -s -v tests/test_codecs.py

Expected Behavior
Test passes without syntax errors.

Actual Behavior
A GaussDBSyntaxError occurs due to an issue with the parameter placeholder "$1" in the SQL query.

Environment

• OS: Huawei Cloud EulerOS 2.0
• Database: GaussDB Kernel 505.2.1.SPC0800 build 3e43b3bc