Add a git attribute to only show the tag name, without suffixes

[marcospereira]

The current git.tag attribute shows the full description of the tag, with a suffix including the number of additional commits on top of the tagged object and the abbreviated object name of the most recent commit. The current output would be:

3.1.2-beta5-17-g7c2d387

Where -17-g7c2d387 is the suffix.

While this is useful in some cases, having only the tag name with no suffix is useful when showing the latest release. The abbreviated tag name would be:

3.1.2-beta5

And this can later be used when linking to code in that tag:

See the [setup](https://github.com/fralau/mkdocs_macros_plugin/blob/{{ git.short_tag }}/setup.py) code.

To the release itself:

See the [release notes for the latest release](https://github.com/fralau/mkdocs_macros_plugin/releases/tag/{{ git.short_tag }}).

Or, depending on the tag name, even adding code snippets such as:

Add it as a requirement:

    extras_require={
        'test': ["some-package>={{ git.short_tag }}],
    }

[github-actions[bot]]

Welcome to this project and thank you!' first issue

[fralau]

From a first examination, it makes sense.

Where would you use that statement?

    extras_require={
        'test': ["some-package>={{ git.short_tag }}],
    }

[marcospereira]

Where would you use that statement?

In a markdown doc that describes how to use a dependency. I copied from this project itself. But think about this doc here:

https://jte.gg/#getting-started

The markdown source would be:

<dependency>
    <groupId>gg.jte</groupId>
    <artifactId>jte</artifactId>
    <version>{{ git.short_tag }}</version>
</dependency>