Use PHPunit 5.7 in all test jobs

Author: wouterj

.travis.yml

@@ -9,9 +9,11 @@ sudo: false
 cache:
   directories:
     - $HOME/.composer/cache/files
+    - .phpunit
 
 env:
   - SYMFONY_VERSION=3.2.*
+  - SYMFONY_PHPUNIT_DIR=.phpunit SYMFONY_PHPUNIT_VERSION=5.7
 
 matrix:
   include:
@@ -32,7 +34,7 @@ before_install:
 
 install: composer update --prefer-dist $COMPOSER_FLAGS
 
-script: phpunit
+script: vendor/bin/simple-phpunit
 
 notifications:
   irc: "irc.freenode.org#symfony-cmf"