Add support for slideshows using sphinx-carousel

sphinx-carousel is a Sphinx extension for creating slideshows using
Bootstrap carousels. The extension supports the PyData Sphinx theme that
we are currently using.

This would be a nice addition to show the various steps of an algorithm
in swh-alter documentation.

See: https://sphinx-carousel.readthedocs.io/ and
https://getbootstrap.com/docs/5.1/components/carousel/

requirements.txt

@@ -5,6 +5,7 @@ sphinx
 sphinxcontrib-httpdomain >= 1.8.0
 sphinxcontrib-images
 sphinxcontrib-programoutput
+sphinx-carousel
 sphinx-design
 sphinx-reredirects
 pydata-sphinx-theme

swh/docs/sphinx/conf.py

@@ -42,6 +42,7 @@ extensions = [
     # swh.scheduler inherits some attribute descriptions from celery that use
     # custom crossrefs (eg. :setting:`task_ignore_result`)
     "sphinx_celery.setting_crossref",
+    "sphinx_carousel.carousel",
     "sphinx_design",
 ]