Check git history up to `.cargo_vcs_info.json` sha

[Marco Ieni]

Motivations

For weird issues, it can happen that release-plz checks the entire history of the project, which is wrong, because it will report the entire repo history in the changelog.

Solution

We can use the sha1 contained in the .cargo_vcs_info.json file, which is included on cargo publish if --allow-dirty is not included.
Docs here.

In the diff algorithm we should stop if we reached this commit. Similar to how we do here:

release-plz/crates/release_plz_core/src/next_ver.rs

Line 975 in b1ad2f5

 || is_commit_too_old(repository, tag_commit.as_deref(), &current_commit_hash) 

Don't assume this file always exist.