Add additional dependencies from setup.cfg.

This is an attempt to square up dependencies between stdeb.cfg and
setup.cfg.

This presents a problem for platform support since some packages like
myst-parser and exhale are not available on Ubuntu Focal.
Therefore, we have to drop focal in order to package rosdoc2.

stdeb.cfg

@@ -1,5 +1,5 @@
 [rosdoc2]
 No-Python2:
-Depends3: python3-breathe, python3-catkin-pkg-modules, python3-osrf-pycommon, python3-setuptools, python3-sphinx, python3-yaml, doxygen
-Suite: focal jammy noble bookworm trixie
+Depends3: python3-breathe, python3-catkin-pkg-modules, python3-exhale, python3-jinja2, python3-myst-parser, python3-osrf-pycommon, python3-setuptools, python3-sphinx, python3-sphinx-rtd-theme, python3-yaml, doxygen
+Suite: jammy noble bookworm trixie
 X-Python3-Version: >= 3.6