Removal of all pre-v1.1 versions of PyUAVCAN from PyPI

I am going to pull all releases of PyUAVCAN from PyPI prior to v1.1.0.dev0 because currently, the Python ecosystem prefers older releases if they do not contain .dev in the tag.

https://pypi.org/project/pyuavcan/#history

If you do pip install pyuavcan you end up with an old version which is bad. Removal of older pre-release versions will make this behavior explicit and thus more manageable.

If there are objections, please speak up now.