Both were exact-pinned to 2023/2024 releases with no prebuilt wheels
for Python 3.14, which GitHub's ubuntu-latest runner image now ships
by default. pip falls back to building from source, and rpds-py's
build (via pyo3 0.20.3) hard-rejects any Python newer than 3.12.

Switching to minimum-version floors lets pip resolve whatever current
release has a prebuilt wheel for the Python actually present, instead
of needing a manual pin bump every time the runner's default Python
changes. Verified locally: cffi==1.16.0/rpds-py==0.18.1 fail to build
on python:3.14-slim; cffi>=1.17.0/rpds-py>=0.20.0 install cleanly
there, and the full requirements.txt installs end-to-end on 3.14.