Upgrade to gix v0.45 for multi-round pack negotiations.

Previously, fetches and clones would routinely fail with a panic
that indicated that pack-negotiation can't take longer than 1 round
with our previous `Naive` approach.

With this version of `gitoxide` there is now faithful support for both
the `consecutive` and the `skipping` algorithm and multiple rounds of
negotiations, which should make all clones and fetches possible.