Bug#1085158: [Pkg-rust-maintainers] Bug#1085158: please upgrade to v0.66

[Fabian Grünbichler]

gix 0.64 should be on its way to the archive now! cargo upstream is still at 
0.64 atm, so this will remain the packaged version for at least the next ~6 
weeks or so. please holler if there's anything needed other than a full update 
of the whole gix-* stack (i.e., if a backport of a compatible upstream change 
unblocks something on your end).