Unpin `sphinxcontrib-...` packages back

[erogluorhan]

Several sphinxcontrib-... packages' new versions have been released over the weekend of Jan 13 & 14, 2024, and they started to require Sphinx 5.0 that led our cookbook builds to fail.

To temporarily overcome this situation, PR #91 and PR #92 have been realized. Once the permanent Sphinx theme update is performed (in ProjectPythia/sphinx-pythia-theme - Issue #39), these PR's pinnings need to be reverted.

[brian-rose]

Now that pythia-sphinx-theme v2024.3.0 is released, it's time to remove these pins.