Get rid of Travis warnings

Author: schlessera

.travis.yml

@@ -1,4 +1,5 @@
-dist: trusty
+os: linux
+dist: xenial
 language: php
 
 branches:
@@ -7,15 +8,13 @@ branches:
     - master
     - /^[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+.*$/
 
-matrix:
+jobs:
   fast_finish: true
   include:
     - php: 7.4
     - php: 7.3
     - php: 7.2
 
-sudo: false
-
 cache:
   directories:
     - $HOME/.composer/cache