ci: Travis: dist=xenial

.travis.yml

@@ -1,4 +1,4 @@
-sudo: false
+dist: xenial
 language: python
 
 notifications:
@@ -17,9 +17,9 @@ install:
 script: tox
 
 stages:
-- baseline
-- test
-- name: deploy
+  - baseline
+  - test
+  - name: deploy
     if: repo = pytest-dev/pytest-xdist AND tag IS present
 
 jobs:
@@ -39,8 +39,6 @@ jobs:
       env: TOXENV=py35-pytestlatest
     - python: "3.7"
       env: TOXENV=py37-pytestlatest
-      sudo: required
-      dist: xenial
     - python: "2.7"
       env: TOXENV=py27-pytestmaster
     - python: "2.7"