Use "sphinx-build" instead of "setup.py build_sphinx"

tools/docker/doc-watch.sh

@@ -3,11 +3,11 @@
 #
 cd /source
 # Build once first
-sudo -u nav python3 setup.py build # ensure build data and .eggs aren't stored as root
-python3 setup.py develop
-sudo -u nav python3 setup.py build_sphinx
+sudo -u nav python3 -m build # ensure build data and .eggs aren't stored as root
+pip install -e .
+sudo -u nav sphinx-build doc/ doc/_build
 # Then re-build on any changes to the doc directory
 while inotifywait -e modify -e move -e create -e delete -r --exclude \# /source/doc /source/NOTES.rst
 do
- sudo -u nav python3 setup.py build_sphinx
+ sudo -u nav sphinx-build doc/ doc/_build
 done

tox.ini

@@ -112,7 +112,7 @@ commands_pre =
  pip-compile --resolver=backtracking --output-file {envdir}/requirements.txt doc/requirements.txt
  pip-sync {envdir}/requirements.txt
 commands =
- python setup.py build_sphinx
+ sphinx-build doc/ doc/_build/
  sh -c "cd doc; python -c 'import conf; print(conf.version)' > {toxinidir}/reports/doc_version"
 
 # The flake8 setup should mirror the setup in pre-commit