Update .travis.yml

Author: hardevine

.travis.yml

@@ -1,11 +1,10 @@
 language: php
 
 php:
-  - 5.6
   - 7.0
 
 before_script:
   - composer self-update
   - composer install --prefer-source --no-interaction
 
-script: vendor/bin/phpunit
+script: vendor/bin/phpunit