typing: enable pytype processing on mercurial/upgrade_utils/actions.py
This was the suggested workaround for the pytype bug that caused this file to be
processed forever.
Differential Revision: https://phab.mercurial-scm.org/D10460
$ LANG=nonexistent LC_ALL=nonexistent LANGUAGE=nonexistent hg version -q
Mercurial Distributed SCM (version *) (glob)