hgweb: remove Python 3 conditional
We probably have a better tobytes() implementation somewhere in pycompat.
But I don't want to bloat scope of this commit.
Differential Revision: https://phab.mercurial-scm.org/D12308
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}