Uses git-based package registry instead of sparse registry by default

[w-flo]

Thank you for cargo-geiger!

Cargo has now switched to using the sparse registry by default, so I have removed the git-based registry files from my system. However, when I try to use current cargo-geiger 0.11.6, it will download the old git-based registry again.

I believe it should be enough to bump the cargo dependency in cargo-geiger to 0.71 to fix this. At least it seemed to work for cargo-outdated.