Use sphinx 1.8 for now

maxnoe · maxnoe · commit fde7bb4107df · 2019-04-15T14:45:03.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -16,7 +16,7 @@ before_install:
   - pip install --upgrade pip
 
 install:
-  - pip install restructuredtext-lint sphinx pygments
+  - pip install restructuredtext-lint sphinx~=1.8 pygments
   - pip install .
 
 script:
