[travis-ci] Fix composer install
[travis-ci] Fix composer install

Bug introduced in fa83f08a6e61896b594395f618f8ee1e4807005f

MadCat34/zend-eventmanager,codeliner/zend-eventmanager,Maks3w/zend-eventmanager,matwright/zend-eventmanager,ezimuel/zend-eventmanager