i18n: fix coding tag unsupported by xgettext Running `make update-pot` currently fails with the following error: xgettext: mercurial/metadata.py:1: Unknown encoding "utf8". Proceeding with ASCII instead. xgettext: Non-ASCII string at mercurial/metadata.py:311. Please specify the source encoding through --from-code or through a comment as specified in http://www.python.org/peps/pep-0263.html. Differential Revision: https://phab.mercurial-scm.org/D9260

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