Python 3.10 即将到达 EOL（2026-10），建议移除未使用的 ujson 并支持到 3.12

README currently requires Python==3.10.16, and according to the official plan, Python 3.10 will be End-of-life (PEP 619, official version status table) in **2026-10**, which is only about a week away. After that, there will be no security patches available. Some versions in requirements.txt are also stuck at 2022~2023, such as `ujson==5.1.0`, which does not even have the wheel for the new Python, and compiling on 3.12 fails directly (see #828). It is recommended to push the Python support window forward, and not to keep waiting for 3.10.