use git ls-tree --format instead of manually carving hashes

[klensy]

https://git-scm.com/docs/git-ls-tree#Documentation/git-ls-tree.txt---formatltformatgt
--object-only can be used only from git 2.36 version.

[rustbot]

r? @clubby789

(rustbot has picked a reviewer for you, use r? to override)

[clubby789]

Looks like the version of Git in CI is 2.34.1, and this option was added in git 2.40.0.

[clubby789]

I'm not sure --format is available either; https://git-scm.com/docs/git-ls-tree/2.34.1

[klensy]

I'm not sure --format is available either; https://git-scm.com/docs/git-ls-tree/2.34.1

CI runner is 2.40.1, but dockered ubuntu 22.04 is 2.34.1, yeah.

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

   Compiling clap v4.2.4
   Compiling clap_complete v4.2.2
    Finished dev [unoptimized] target(s) in 14.97s
##[endgroup]
error: unknown option `format=%(objectname)'
usage: git ls-tree [<options>] <tree-ish> [<path>...]

    -d                    only show trees
    -r                    recurse into subtrees
    -t                    show trees when recursing
    -z                    terminate entries with NUL byte
    -l, --long            include object size
    --name-only           list only filenames
    --name-status         list only filenames
    --full-name           use full path names
    --full-tree           list entire tree; not just current directory (implies --full-name)
    --abbrev[=<n>]        use <n> digits to display object names

thread 'main' panicked at 'command did not execute successfully: cd "/checkout" && "git" "ls-tree" "HEAD" "src/tools/cargo" "--format=%(objectname)"
expected success, got: exit status: 129', lib.rs:550:27
Build completed unsuccessfully in 0:00:25

[klensy]

Sad.