Support for Python 3.8

[fkromer]

As kedro is Python 3.8 compatible now it would be great if you could add support for Python 3.8:

$ kedro --version
kedro, version 0.16.1
$ pip3 install --user kedro-static-viz
Collecting kedro-static-viz
  Using cached kedro_static_viz-0.1.3-py3-none-any.whl (429 kB)
Requirement already satisfied: click in /home/florian/.local/lib/python3.8/site-packages (from kedro-static-viz) (7.1.2)
Requirement already satisfied: kedro in /home/florian/.local/lib/python3.8/site-packages (from kedro-static-viz) (0.16.1)
ERROR: Could not find a version that satisfies the requirement kedro-viz (from kedro-static-viz) (from versions: none)
ERROR: No matching distribution found for kedro-viz (from kedro-static-viz)

[WaylonWalker]

@fkromer thanks for raising and engaging in the project, your awesome!

I was waiting for kedro-viz to go 3.8, but actually I can pull that dependecy and go up to 3.8.

I've been meaning to hard code the json creation function anyways as it is a private function in kedro-viz.

[WaylonWalker]

This was resolved in #3