The version 3.21 isn't compatible with our currently packaged
`pythonPackages.gpapi` which is now at version 0.4.3.
See https://hydra.nixos.org/build/83154918
The `buildPython*` function computes name from `pname` and `version`.
This change removes `name` attribute from all expressions in
`pkgs/development/python-modules`.
While at it, some other minor changes were made as well, such as
replacing `fetchurl` calls with `fetchPypi`.