CI(.travis.yml): Install forgotten `ppu`

diff --git a/.travis.yml b/.travis.yml
index 51c28ccde1c6817419be72b61857d3a53daca6a3..afe6f972a2d1a0687f9fecc27bb313491b0c2250 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,7 +32,7 @@ matrix:
     env: TOXENV=pypy
 
 install:
-  - travis_retry pip install --upgrade pip setuptools tox
+  - travis_retry pip install --upgrade pip setuptools tox ppu
 
 script:
   - tox