Rust 1.80.1 will break Dependabot unit test

[RobJellinghaus]

Code improvement description

I am working on various Rust/Cargo-related Dependabot issues, and as part of this I have been testing with a newer version of Rust than the current 1.79 included in dependabot-core today.

This turned up an error message change in Rust version 1.80 when fetching a nonexistent git reference. This error message change actually breaks an existing Dependabot unit test, specifically this one: https://github.com/dependabot/dependabot-core/blob/main/cargo/spec/dependabot/cargo/update_checker/version_resolver_spec.rb#L355

I have filed this issue in the Cargo project: rust-lang/cargo#14621

It looks like the Cargo team may do something about it. But in the meantime, I plan to work on a Dependabot change to deal with the new error message format, to allow Dependabot to move forward to a newer Rust version.

I am filing this issue to make the Dependabot team aware of the situation.