Genbadge

- `setup.py` is now using the contents of `setup.cfg` for download url and setuptools_scm. There is now a single configuration file. See [setuptools_scm582](https://github.com/pypa/setuptools_scm/issues/582).

- Fixed the release message.

- `genbadge coverage` command: fixed `ImporError` with `defusedxml`. Fixed [14](https://github.com/smarie/python-genbadge/issues/14).

- The tests badge now simplifies when the success rate is 100%, which is the case in the vast majority of projects. Fixes [12](https://github.com/smarie/python-genbadge/issues/12)

- Now using `defusedxml` to fix a [known vulnerability](https://docs.python.org/3/library/xml.etree.elementtree.html). Fixes [#11](https://github.com/smarie/python-genbadge/issues/11)

- Added `flake8` command. Fixes [3](https://github.com/smarie/python-genbadge/issues/3).
- Added a "silent" flag `-s`. Fixes [10](https://github.com/smarie/python-genbadge/issues/10)
- Added a verbosity flag `-v`. Fixes [1](https://github.com/smarie/python-genbadge/issues/1)
- Python 3.9 is now officially supported. Fixes [9](https://github.com/smarie/python-genbadge/issues/9)

- Fixed bug with writing to stdout. Fixed [8](https://github.com/smarie/python-genbadge/issues/8).