Update dependencies once mholt/archiver#92 has landed

[jandubois]

Waiting for mholt/archiver#92

We have a local change to the vendored dependency in #414, which should be replaced by the proper fix as soon as available.

[jandubois]

Upstream has been updated, so we can move to the latest archiver now. Commit f11b26d shows source code changes required for the new API.