Update pypi repo

The version here in the repository contains the latest bugfix which is needed for using the library.
Unfortunately, the current version in [pypi](https://pypi.org/project/arrowhead-client/) doesn't contain the fix. Maybe it's the caching issue again.

As workaround:
Checkout the repo and build your own `.whl` file from it.
e.g. `pip wheel -e . -w wheels --no-deps`

Then, you use it in your new project, e.g:
`pip install arrowhead-client arrowhead_client-0.4.3a0-py3-none-any.whl`

On the long run it would be nice to have the current latest version in the pypi repo.

Start in the repository by checking the current package version and running the reported `pip wheel -e . -w wheels --no-deps` command. Compare the resulting package with the version published at PyPI, then determine the repository's release steps. Done means the latest bugfix is available as the current installable `arrowhead-client` version on PyPI.

Written by the indexing model from the issue text.