fix: json_serial returns bytes instead of str for non-UTF-8 binary va… - #2414

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-python@v5, suo/flake8-github-action@releases/v1. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/