test: pg_dump_roundtrip gets its pytest twin, and its index and sort_by arms test what they name (#1341) - #1458

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/