Fix: Use the same version of phpunit/phpunit on Travis as required
Fix: Use the same version of phpunit/phpunit on Travis as required

mfn/raven-php,madssj/raven-php,getsentry/raven-php,theand/raven-php,ManhattanPrep/raven-php,ste93cry/sentry-php,patrick91/raven-php,cpascal/raven-php,nokitakaze/sentry-php,getsentry/sentry-php,getsentry/sentry-php