Merge branch 'ast-933-sphinx-only' into 'main'

.gitlab-ci.common.yml

CMakeLists.txt

cmake/FindSphinx.cmake

cpp/radler.h

cpp/settings.h

doc/CMakeLists.txt

doc/Doxyfile.in

doc/build-instructions.rst

doc/conf.py

doc/index.rst

doc/indices-and-tables.rst

doc/tree/cpp-interface.rst

doc/tree/cpp/algorithms.rst

doc/tree/cpp/settings.rst

doc/tree/interfaces-overview.rst

doc/tree/python-interface.rst

doc/tree/python/settings.rst

docker/ubuntu_20_04_base

docker/ubuntu_22_04_base

python/pysettings.cc