Update .travis.yml

Author: yakeing

.travis.yml

@@ -16,10 +16,6 @@ before_install:
   - tar -zcf /tmp/Core.tar.gz src
   - cd tests
 
-before_script:
-    - travis_retry composer self-update
-    - travis_retry composer install --no-interaction --prefer-source --dev
-
 script:
     - phpunit --stderr
     - vendor/bin/phpunit --coverage-clover=coverage.xml