travis: Add python3-sphinx to the package list

In order to build htmldocs we need sphinx-build which comes from
python3-sphinx.

Signed-off-by: Tom Rini <trini@konsulko.com>

diff --git a/.travis.yml b/.travis.yml
index e6db9d6a721a1518a008e19fb6066929acfecb29..11f9757d889f7c41a05b3d775e633b532fe5837a 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,6 +22,7 @@ addons:
     - libsdl2-dev
     - python
     - python-pyelftools
+    - python3-sphinx
     - python3-virtualenv
     - python3-pip
     - swig