CI: Clean up travis.yml

Author: effigies

.travis.yml

@@ -1,3 +1,4 @@
+os: linux
 dist: xenial
 sudo: true
 
@@ -8,15 +9,13 @@ python:
 - 3.6
 - 3.7
 
-# NOTE: Any changes to the matrix section should be duplicated below for
-#       Python 3.4
 env:
   global:
     - EXTRA_WHEELS="https://5cf40426d9f06eb7461d-6fe47d9331aba7cd62fc36c7196769e4.ssl.cf2.rackcdn.com"
     - PRE_WHEELS="https://7933911d6844c6c53a7d-47bd50c35cd79bd838daf386af554a83.ssl.cf2.rackcdn.com"
     - EXTRA_PIP_FLAGS="--find-links=$EXTRA_WHEELS"
     - CHECK_TYPE=test
-  matrix:
+  jobs:
     - INSTALL_DEB_DEPENDECIES=true
       NIPYPE_EXTRAS="doc,tests,nipy,profiler"
       CI_SKIP_TEST=1
@@ -31,7 +30,7 @@ env:
       EXTRA_PIP_FLAGS="--pre $EXTRA_PIP_FLAGS --find-links $PRE_WHEELS --upgrade"
       CI_SKIP_TEST=1
 
-matrix:
+jobs:
   include:
     - python: 3.7
       env: