[Brook] feat(python): generate a caller per service over a replaceable transport - #39

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: jdx/mise-action@5228313ee0372e111a38da051671ca30fc5a96db. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/