Remove composer self-update

Author: sagikazarmark

.travis.yml

@@ -29,7 +29,6 @@ matrix:
 
 before_install:
     - if [[ $COVERAGE != true && $TRAVIS_PHP_VERSION != hhvm ]]; then phpenv config-rm xdebug.ini; fi
-    - travis_retry composer self-update
 
 install:
     - travis_retry composer update ${COMPOSER_FLAGS} --prefer-dist --no-interaction