Sphinx-nefertiti

- New: Highlight the item in the TOC at the right side ('on this page' column) when the location bar refers to an anchor that is part of the TOC.
- Change: Lighten body background in light color-scheme for all colorsets.

- ReadTheDocs no longer provides versions in the context of the template.
- Update quick-start and version-dropdown documents.
- Update `versions.js` to display the `current_version` given in `conf.py`.

- Increase contrast for body-bg, pre-border-color, and border-color for the light color scheme, in all colorsets.
- Fix colorset selector. Data attributes do not match between JS and HTML.
- Fix light/dark selector. When not 'default', reloading brings back 'default'.
- Update required version of sphinx-colorschemed-images.
- Update `colorsets.rst` in the docs.

- Header and footer links can be references to internal documents or URLs.
- Fix issue in Nefertiti when building the docs in ReadTheDocs.

- Add breadcrumbs.
- Use smooth scrolling.
- Add **back-to-top** button.
- Add customizable header links.
- Limit height of version dropdown.
- Use compact notation to display number of stars, and forks, in header's repository widget.
- Scroll the left sidebar to show the link corresponding to the current page.
- In the sphinx-nefertiti documentation website, reset the colorset selected by the user 24 hours after it has been selected.
- Migrate from `setup.py` and multiple requirements files, to `pyproject.toml`.
- Use tox to run verify that tests pass against multiple versions of Sphinx.

- Remove version constrain for Sphinx 8 in Nefertiti's dependencies.