py-ujson: update to 4.0.1.

4.0.1

Fixed

    Fix UnicodeDecodeError on arm64/aarch64 (#435) @hugovk

4.0.0

Added

    Add support for Python 3.9 (#430) @hugovk
    Build wheels for Python 3.9 (#431) @hugovk

Removed

    Drop support for EOL Python 3.5 (#424) @hugovk

Fixed

    Fix indent and add test case (#426) @chenhan1218
    Update code samples in README (#427) @verhovsky

3.2.0

Added

    Make PEP 384 compliant (#417) @tekknolagi
    Build and deploy aarch64 wheels (#422) @geoffreyblake

3.1.0

Added

    PEP 489 Multi Phase Init support (#418) @WillAyd

Fixed

    PyPy3 test fixes (#413) @mgorny

(wiz)