update virtualenv version for travis

tsolakoua · tsolakoua · commit 4a9fc9108873 · 2020-02-11T09:15:26.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -10,7 +10,7 @@ branches:
     - master
     - /^v[0-9]/
 before_install:
-  - pip install virtualenv==15.2.0 
+  - pip install virtualenv==20.0.1
   - pip install tox-travis
 script:
   - tox
