Refactor sphinx config and bump docs python version

[sduquemesa]

Context: Sphinx doc builds were failing due to dependencies on deprecated or old package version when building the docs

Description of the Change: This PR

• refactors the .readthedocs.yml configuration file to set the container version of the readthedocs builder
• bumps python version of the sphinx container to v3.10
• unpins requirements in doc/requirements.txt to use the latest version available of packages

Benefits: Docs build and hopefully will continue to do so as dependent packages get upgraded

Possible Drawbacks: Doc requirements is now unpinned

Related GitHub Issues: None

[nquesada]

Thanks @sduquemesa !

[codecov[bot]]

Codecov Report

Merging #364 (8cac798) into master (43757a9) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

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