.arcconfig

contrib: print the version of pytype used to do the type checking

This will help with CI.  I don't see a way to print the version of python that's
running it.  When I tried `head -n 1 $(which pytype)`, the CI run printed:

    #!/usr/bin/env bash

Locally, that gives the path to the python interpreter in the venv, so IDK
what's different.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "phabricator.uri": "https://phab.mercurial-scm.org/",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}