python3Packages.pyvips: fix on darwin-aarch64 by providing pkg-config
python3Packages.pyvips: fix on darwin-aarch64 by providing pkg-config

...as well as the python package `pkgconfig`. the native `pkg-config`
tool is used by the installer to locate the vips headers. if it can't
do this it falls back into using libffi's "ABI mode" which results in
the issues documented at
https://cffi.readthedocs.io/en/latest/using.html#callbacks on
darwin-aarch64.

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