Update .travis.yml

Author: ghalse

.travis.yml

@@ -38,7 +38,8 @@ before_install:
     " simplesamlphp
 
 before_script:
-  composer update --dev
+  - composer update
+  - if [[ "$TRAVIS_PHP_VERSION" == "7.2" ]]; then echo 'error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT' >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini; fi
 
 script:
   php vendor/phpunit/phpunit/phpunit