The configuration of caucase used here is to have certificates valid for
3*31 days and renew them 31 days before the expiration date.
This test was running the updater 2 months later, which by chance was
62 days at the time of the test was written, because this test was
written in July (both July and August have 31 days), but this does not
work in other months.
Adjust the test to run the updater using a fixed number of days in the
future.

Because dufs only reads certificate on startup it does not detect when
the certificate was renewed.

The only thing supported by dufs is to restart, so we use hash-files
options of wrapper recipe to

Also switch to basic authentication, this is generally more supported
than digest; keeweb for example only supports basic authentication. It
seems less secure though ( https://github.com/sigoden/dufs/issues/228 )