Updated travis to deprecate Python 3.5

.travis.yml

@@ -2,10 +2,10 @@ language: python
 dist: xenial
 matrix:
   include:
+    - python: 3.9
     - python: 3.8
     - python: 3.7
     - python: 3.6
-    - python: 3.5
 install:
   - "pip install tox-travis tox==3.14.6 coveralls"
   - "pip install -e ."