Remove GH Action Test Doc Creation (Sphinx)

[hf-krechan]

During my work on the sphinx / readthedocs documentation I added another check.
This check tries to build the documentation directly on readthedocs in each PR.
So if you are working on the documentation you can immediately see the result on readthedocs.

Due I think we do not need this docs test cause it is redundant.

As an example you can check this PR: #673
By clicking on details on the readthedocs check, you can access directly the newest documentation.

[hf-krechan]

removed tox docs from GH actions in #697