dbg: ensure 1 process

Author: jorgepiloto

tox.ini

@@ -92,7 +92,7 @@ extras =
     visualization
 commands =
     sphinx-build -d "{toxworkdir}/doc_doctree" doc/source "{toxinidir}/doc/_build/linkcheck" --color -vW -b linkcheck -j auto
-    sphinx-build -d "{toxworkdir}/doc_doctree" doc/source "{toxinidir}/doc/_build/html" --color -vW -b html -j auto
+    sphinx-build -d "{toxworkdir}/doc_doctree" doc/source "{toxinidir}/doc/_build/html" --color -vW -b html -j 1
 
 # The following environments are only for development purposes. Do not use in CI/CD.
 # Using these during a CI/CD can lead to unexpected issues due to a Docker-In-Docker