python3Packages.pbr: add setuptools dependency
python3Packages.pbr: add setuptools dependency

pbr doesn't list any explicit requirements, but it actually requires
setuptools (for pkg_resources).
Ref:
* https://bugs.launchpad.net/pbr/+bug/1868899
* https://opendev.org/openstack/pbr/src/tag/5.6.0/pbr/version.py#L439

(cherry picked from commit 21d70a8301b2ee5c063ca953aa6748d554301ef8)

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs