Fix GH Actions failing due to a change in Sphinx.

[krisfremen]

Pull Request Checklist

• [ ] 🧪 Added tests for changed code.
• [ ] 🛠️ All tests pass when run locally (run tox or make test to find out!).
• [ ] 🧹 All linting checks pass when run locally (run tox -e lint or make lint to find out!).
• [ ] 📚 Updated documentation for changed code.
• [x] ⏩ Code is up-to-date with the master branch.

Description of Changes

Fixes github actions that have been failing since the release of Sphinx 5.x where they deprecate usage of None for language in conf.py

[codecov[bot]]

Codecov Report

Merging #1114 (55d7d36) into master (4357f8c) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1114   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines         2314      2314           
  Branches       448       448           
=========================================
  Hits          2314      2314           

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