incorrect 'git' version for GitPython==3.1.28 installed from PyPI

It looks like there's mistake in the release of GitPython 3.1.28 with respect to the version.

Here's the output I'm getting when GitPython 3.1.28 is installed (using `pip3 install`)

```
$ python3 -c 'import git; print(git.__version__)'
git
```

With older GitPython versions, I'm getting a proper version instead:

```
$ python3 -c 'import git; print(git.__version__)'
3.1.27
```