Python 3.13.2: TestConnectParams.test_connect_params fails with ValueError: Invalid IPv6 URL

Nobody has claimed this yet.

Based on historical test-builds of the [`python-asyncpg` package in Fedora](https://src.fedoraproject.org/rpms/python-asyncpg), this appears to be a regression from Python 3.13.1 to 3.13.2.

```
$ python3.13 --version
Python 3.13.2
$ python3.13 -m venv _e
$ . _e/bin/activate
(_e) $ pip install -e .[gssauth,test]
(_e) $ pip install pytest
(_e) $ python -m pytest
[…]
========================================================================================== short test summary info ===========================================================================================
FAILED tests/test__sourcecode.py::TestCodeQuality::test_flake8 - AssertionError: flake8 validation failed:
FAILED tests/test_codecs.py::TestCodecs::test_custom_codec_binary - asyncpg.exceptions.FeatureNotSupportedError: extension "hstore" is not available
FAILED tests/test_codecs.py::TestCodecs::test_custom_codec_text - asyncpg.exceptions.FeatureNotSupportedError: extension "hstore" is not available
FAILED tests/test_codecs.py::TestCodecs::test_extra_codec_alias - asyncpg.exceptions.FeatureNotSupportedError: extension "hstore" is not available
FAILED tests/test_codecs.py::TestCodecs::test_unhandled_type_fallback - asyncpg.exceptions.FeatureNotSupportedError: extension "isn" is not available
FAILED tests/test_codecs.py::TestCodecs::test_unknown_type_text_fallback - asyncpg.exceptions.FeatureNotSupportedError: extension "citext" is not available
FAILED tests/test_connect.py::TestConnectParams::test_connect_params - ValueError: Invalid IPv6 URL
FAILED tests/test_connect.py::TestConnectionAttributes::test_prefer_standby_picks_master_when_standby_is_down - TimeoutError
FAILED tests/test_introspection.py::TestIntrospection::test_introspection_no_stmt_cache_01 - asyncpg.exceptions.FeatureNotSupportedError: extension "hstore" is not available
FAILED tests/test_introspection.py::TestIntrospection::test_introspection_no_stmt_cache_02 - asyncpg.exceptions.FeatureNotSupportedError: extension "hstore" is not available
===================================================================== 10 failed, 300 passed, 3 skipped, 3 warnings in 132.00s (0:02:12) ======================================================================
```

The subject of this report is:

```
FAILED tests/test_connect.py::TestConnectParams::test_connect_params - ValueError: Invalid IPv6 URL
```

The full output for that failure is:

```
___________________________________________________________________________________ TestConnectParams.test_connect_params ____________________________________________________________________________________
Traceback (most recent call last):
File "/usr/lib64/python3.13/unittest/case.py", line 58, in testPartExecutor
yield
File "/usr/lib64/python3.13/unittest/case.py", line 651, in run
self._callTestMethod(testMethod)
~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
File "/usr/lib64/python3.13/unittest/case.py", line 606, in _callTestMethod
if method() is not None:
~~~~~~^^
File "/home/ben/src/forks/asyncpg/tests/test_connect.py", line 1237, in test_connect_params
self.run_testcase(testcase)
~~~~~~~~~~~~~~~~~^^^^^^^^^^
File "/home/ben/src/forks/asyncpg/tests/test_connect.py", line 1154, in run_testcase
addrs, params = connect_utils._parse_connect_dsn_and_args(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
dsn=dsn, host=host, port=port, user=user, password=password,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...<3 lines>...
target_session_attrs=target_session_attrs,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
krbsrvname=krbsrvname, gsslib=gsslib)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ben/src/forks/asyncpg/asyncpg/connect_utils.py", line 282, in _parse_connect_dsn_and_args
parsed = urllib.parse.urlparse(dsn)
File "/usr/lib64/python3.13/urllib/parse.py", line 395, in urlparse
splitresult = urlsplit(url, scheme, allow_fragments)
File "/usr/lib64/python3.13/urllib/parse.py", line 516, in urlsplit
_check_bracketed_netloc(netloc)
~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
File "/usr/lib64/python3.13/urllib/parse.py", line 451, in _check_bracketed_netloc
raise ValueError("Invalid IPv6 URL")
ValueError: Invalid IPv6 URL
```

Start with tests/test_connect.py::TestConnectParams::test_connect_params and reproduce the failure on Python 3.13.2. Read asyncpg/connect_utils.py around _parse_connect_dsn_and_args and urllib.parse.urlparse; done means the targeted test no longer raises ValueError: Invalid IPv6 URL.

Written by the indexing model from the issue text.