Gix 0.74

[djc]

Checklist

• I have read the Contributor Guide
• I have read and agree to the Code of Conduct
• I have added a description of my changes and why I'd like them included in the section below

Description of Changes

Update to latest gix.

[djc]

Okay, this makes gix::ObjectId non-exhaustive, while you currently have a number of irrefutable matches against ::Sha1. It seems useful to start storing a gix::ObjectId internally, but I'm not sure exactly how you might want to pursue that (ValidCacheEntry currently stores a &str that may also represent a sparse index HTTP header value -- might be sensible to use a wrapping enum for that?). Happy to help if you want to outline the desired direction -- also fine if you just want to close this.