hghave: make black version regex work with newer versions of black
Black commit 117891878e5be4d6b771ae5de299e51b679cea27 (included in black >=
21.11b0) dropped the string "version " from the output of "black --version". To
make the regex work with newer black versions, make matching of "version "
optional.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}