Update .travis.yml to be compatible with latest travis cfg specs (coo…

…kiecutter#1346)

- Removed "sudo: false" because is deprecated

- Renamed "matrix" to "jobs" because "matrix" is deprecated

- Added "os: linux" because now the "os" is required on the root section

.travis.yml

@@ -1,9 +1,9 @@
 # Config file for automatic testing at travis-ci.org
 dist: xenial
-sudo: false
+os: linux
 language: python
 
-matrix:
+jobs:
     include:
       - python: 3.7
         env: TOXENV=lint