Sphinx-tabs

Fixed

* 🐛 Added default value for `exports` in JavaScript. Removes error that `exports` is not defined on page

Added

* 👌 Use of [`sphinx` HTML assets policy](https://github.com/sphinx-doc/sphinx/issues/9115) to decide whether include assets

Added

* 👌 Added new sphinx config `sphinx_tabs_disable_css_loading` option to disable css from loading

Fixed

* 🐛 Update for compatibility with Sphinx 4

Fixed

* 🐛 Tabs with nested content becoming hidden on click

Improved

* 👌 Added new sphinx config option `sphinx_tabs_disable_tab_closing` to allow new tab closing functionality to be disabled globally (better backwards compatibility with sphinx-tabs<2)

Fixed

* Nested parsing of tab labels, to support use of reST roles within label text
* Parsing tabs with unsupported builders, including for pdf

Added

* Test for successful pdf building using `rinohtype`

♻️ Refactor to reduce JS/CSS payload size and improve accessibility:

* Removed semantic-ui assets
* Removed unused 'sphinx_tabs_nowarn' sphinx option
* JS/CSS assets are now copied across by sphinx when builing, rather than being copied by the extension
* Changed tab HTML to use tab roles
* Changed tab label colour, to increase contrast with background
* Added ARIA labels for tabs and panels
* Added tabindex attributes to allow users to focus and switch tabs using a keyboard
* Added a margin below images inside tab content

✨ New features:

* Selecting an open tab now closes the tabs panel
* The last selected group tab persists between pages (if the browser supports session storage)