nixos/anki-sync-server: fix NixOS test (#466334)

    #!${pkgs.python3}/bin/python

    import sys

    import os

    # get site paths from anki itself

    from runpy import run_path

    run_path("${pkgs.anki}/bin/.anki-wrapped")

    import anki

    # anki is built with buildPythonApplication.

    # anki.lib is not a 'proper' python library, meaning it

    # is not recognized in 'withPackages' (due to hasPythonModule in

    # https://github.com/NixOS/nixpkgs/blob/7ef35a9f3abb638647d68b10cccae549094b8054/pkgs/development/interpreters/python/python-packages-base.nix#L89

    # and contains the collection of all python libraries used

    # by anki rather than just the anki itself.

    anki_libs = "${pkgs.anki.lib}/${pkgs.python3.sitePackages}"

    if not os.path.isdir(anki_libs):

      print(f"'{anki_libs}' not found, possible python version mismatch")

      exit(1)

    sys.path.append(anki_libs)

    import anki.collection

    col = anki.collection.Collection('test_collection')

    endpoint = 'http://localhost:27701'