Adding .readthedocs.yaml

[Gmerold]

Description

Adds .readthedocs.yaml which will replace the config from RTD GUI.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation
• [x] I have added tests that validate the behaviour of the software
• [x] I validated that new and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have bumped the version of the library