Travis CI: updated Python versions

.travis.yml

@@ -1,10 +1,12 @@
 language: python
 python:
     - "2.7"
-    - "3.2"
-    - "3.3"
     - "3.4"
     - "3.5"
+    - "3.6"
+    - "3.7"
+    - "3.8"
+    - "3.9"
 sudo: false
 install: "pip install -r requirements.txt"
 script: nosetests