More Travis experiments

Author: bachya

.travis.yml

@@ -1,9 +1,15 @@
 ---
 sudo: false
+matrix:
+  fast_finish: true
+  include:
+    - python: "3.5.3"
+    - python: "3.6"
+      after_success: "pipenv run codecov"
+    - python: "3.7"
+      dist: xenial
+
 language: python
-python:
-  - "3.6"
 install: "make init"
 script: "pipenv run make ci"
 cache: "pip"
-after_success: "pipenv run codecov"