Merge branch 'release-2.9.0'

.gitlab-ci.yml

CHANGELOG.txt

CMakeLists.txt

actions/ost-compare-ligand-structures

actions/ost-compare-structures

docker/Dockerfile

modules/base/src/test_utils/compare_files.cc

modules/base/src/test_utils/compare_files.hh

modules/conop/doc/connectivity.rst

modules/conop/doc/functions.rst

modules/conop/src/chemdict_tool.cc

modules/conop/src/compound.hh

modules/conop/src/compound_lib.cc

modules/conop/tests/test_complib.py

modules/conop/tests/testfiles/test_compounds.cif

modules/doc/actions.rst

modules/io/doc/io.rst

modules/io/doc/mmcif.rst

modules/io/doc/structure_formats.rst

modules/io/pymod/CMakeLists.txt