Update .travis.yml

.travis.yml

@@ -3,6 +3,7 @@ services:
 before_script:
   - echo "USE mysql;\nUPDATE user SET password=PASSWORD('dev') WHERE user='root';\nFLUSH PRIVILEGES;\n" | mysql -u root
 install:
+  - apt-get remove phpunit -y
   - wget https://phar.phpunit.de/phpunit-5.7.phar
   - chmod +x phpunit-5.7.phar
   - sudo mv phpunit-5.7.phar phpunit