Travis: Install tox v3.0.0

Tox 3.1.0 / 3.1.1 do not work with our confugiration, see our GitHub issue biopython#1730.
peterjc · Jul 10, 2018 · e534462 · e534462
1 parent 2afe4ec
commit e534462
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/.travis.yml b/.travis.yml
@@ -136,7 +136,7 @@ before_install:
 # This is minimal and used under all stages
 install:
   - pip install --upgrade pip setuptools
-  - pip install tox
+  - pip install tox==3.0.0
   - tox -c .travis-tox.ini -e $TOXENV --notest
 
 script: