pip prod(deps): update pygments requirement from >=2.20.0 to >=2.21.0 - #2264

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v2, diddlesnaps/snapcraft-review-action@v1, snapcore/action-build@v1. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/