fails to build with Python 3.13

asyncpg version: 0.29.0
Python version: 3.13.0rc2
Platform: Linux
Did you install asyncpg with pip?: Yes
If you built asyncpg locally, which version of Cython did you use?: n/a
Can the issue be reproduced under both asyncio and uvloop?: yes

Fails to build on Python 3.13. There's been various API changes.

      asyncpg/pgproto/pgproto.c:23886:18: warning: ‘__pyx_f_7asyncpg_7pgproto_7pgproto_json_encode’ defined but not used [-Wunused-function]
      23886 | static PyObject *__pyx_f_7asyncpg_7pgproto_7pgproto_json_encode(struct __pyx_obj_7asyncpg_7pgproto_7pgproto_CodecContext *__pyx_v_settings, struct __pyx_obj_7asyncpg_7pgproto_7pgproto_WriteBuffer *__pyx_v_buf, PyObject *__pyx_v_obj) {
            |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      /home/username/.pyenv/versions/3.13.0rc2/include/python3.13/cpython/longobject.h:111:17: note: declared here
        111 | PyAPI_FUNC(int) _PyLong_AsByteArray(PyLongObject* v,
            |                 ^~~~~~~~~~~~~~~~~~~

MagicStack / asyncpg

fails to build with Python 3.13 #1181