Try installing requirements before deploying (because the requirements that tox installed aren't available to the Python that Travis PyPI uses for deployment). Ref #934.

Author: jaraco

.travis.yml

@@ -26,6 +26,8 @@ script:
 
  - tox
 
+before_deploy:
+  - pip install -r requirements.txt
 deploy:
   provider: pypi
   # Also update server in setup.cfg