sphinxcontrib-nwdiag does not appear to be maintained anymore [1] and
there have been no releases in nearly 5 years. Statically generate the
images and include them this way. We can revert this change if the
maintainership issue resolves itself.
sphinxcontrib-blockdiag has had activity more recently [2], but it's
still been nearly 3 years. More importantly, we don't actually use it so
there's no reason to keep it around.
[1] https://pypi.org/project/sphinxcontrib-nwdiag/#history
[1] https://pypi.org/project/sphinxcontrib-blockdiag/#history
Change-Id: Ic5244c792acd01f8aec5ff626e53303c1738aa69
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
6512f0140c