Huggingface GIT returns null as Content-Type instead of application/x-git-receive-pack-result
### Describe the bug

We push changes to our datasets programmatically. Our git client jGit reports that the hf git server returns null as Content-Type after a push.

### Steps to reproduce the bug

A basic kotlin application:
```
   val person = PersonIdent(
        "padmalcom",
        "padmalcom@sth.com"
    )

    val cp = UsernamePasswordCredentialsProvider(
        "padmalcom",
        "mysecrettoken"
    )

    val git =
        KGit.cloneRepository {
            setURI("https://huggingface.co/datasets/sth/images")
            setTimeout(60)
            setProgressMonitor(TextProgressMonitor())
            setCredentialsProvider(cp)
        }

    FileOutputStream("./images/images.csv").apply { writeCsv(images) }
    git.add {
        addFilepattern("images.csv")
    }

    for (i in images) {
        FileUtils.copyFile(
            File("./files/${i.id}"),
            File("./images/${i.id + File(i.fileName).extension }")
        )
        git.add {
            addFilepattern("${i.id + File(i.fileName).extension }")
        }
    }

    val revCommit = git.commit {
        author = person
        message = "Uploading images at " + LocalDateTime.now()
            .format(DateTimeFormatter.ISO_DATE_TIME)
        setCredentialsProvider(cp)
    }

    val push = git.push {
        setCredentialsProvider(cp)
    }
```

### Expected behavior

The git server is expected to return the Content-Type _application/x-git-receive-pack-result_.

### Environment info

It is independent from the datasets library.