CIP-2396 Fixes Read The Docs Build Problem

Fixes the issue with Read the Docs failing to build on the latest versions.

There seems to be issues with how RTD interacts with Poetry (Poetry Issue) and that the virtual environment is needed to be enable so that installed packages (such as the sphinx_rtd_theme) can be found.

I followed STS-553 and implemented the changes made in BTN-2301, who are also having similar issue with RTD.