This is a reexport of nixpkgs.writers.writePython3, but the libraries
are passed the package set, like with other writers.
Change-Id: Ia5a2ed1b6b329700836a8575d2bde768bf64fb31
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2311
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>