Makefile: update Git versions

Update Git versions to address several CVEs:

  - CVE-2024-32002, which can lead to arbitrary code execution on
    case-insensitive filesystems when doing recursive clones.

  - CVE-2024-32004, which can lead to arbitrary code execution when
    doing a local partial clones via the filesystem.

  - CVE-2024-32021, which allows an adversary to rewrite files in a
    cloned repository when using local clones with hardlinks.

  - CVE-2024-32021, which can lead to linking to arbitrary files
    accessible to the user when doing local clones via a TOCTOU style
    race.

  - CVE-2024-32465, which can lead to executing arbitrary commands when
    cloning an untrusted local repository.

None of these issues were found to impact Gitaly, but upgrading is the
right thing to do regardless.