Various Python packages that we use do not declare their dependencies correctly using python packaging metadata.

This is not visible in a standard build of the Sage distribution because we manually manage dependencies using Sage-specific dependency information. But it becomes problematic as we move toward using standard Python infrastructure in #29705.

On this ticket we track the upstream issues.

• pplpy: https://gitlab.com/videlec/pplpy/-/issues/23 and https://gitlab.com/videlec/pplpy/-/issues/27
• fpylll: Add install_requires to setup.py/setup.cfg, or add pyproject.toml fplll/fpylll#185
• cypari2: Needs pyproject.toml to declare build-time dependency on cysignals cypari2#93

Depends on #31025

CC: @videlec @malb @tobiasdiez @dimpase

Component: packages: standard

Keywords: sd111

Issue created by migration from https://trac.sagemath.org/ticket/30922