Latest Docker image has old version of the bindings

[IshaanDesai]

In the release guide there are instructions to update the docker image after a release is done. Additionally there are instructions to check if the latest version of the bindings is correctly installed in the image. The latest release is v3.1.1, and the docker image update workflow has been run. Despite this, the bindings version shown in the docker container is v3.0.0.0. The latest version is not shown.

[BenjaminRodenberg]

Let's remove the Docker image. See #228. I think we do not use it anywhere and we also should encourage using venvs instead.

If somebody wants to use a released version this can be done easily with the release on PyPI. If somebody wants to install the develop version: Pip also allows installation from github repositories.

Closing this issue. @IshaanDesai feel free to reopen if you disagree.