v4.0.4 preview 2

this is a preview version for testing. It should enable mypy to analyse readchar. See #100 for details
It should now actually contain the changes and incorperates the updated deploy workflow that allows for releases from development branches

You can install this version via on of the commands:

pip install -U --pre readchar==4.0.4.dev2

pip install -U git+https://github.com/magmax/python-readchar@v4.0.4-dev2