rust-dependencies: update `regex` to 1.3.9
Version `1.3.8` introduces support for empty alternations, which makes
previously disallowed patterns usable in `regex`.
From a user's perspective, this means that glob patterns like `*.py{,c}` will
no longer generate an "invalid" regex and will use the Rust path.
`1.3.9` is a bugfix release, might as well update to the latest one.
Differential Revision: https://phab.mercurial-scm.org/D8593
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}