Removes unnecessary self-update from travis config

Author: weierophinney

.travis.yml

@@ -57,7 +57,6 @@ matrix:
 
 before_install:
   - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi
-  - travis_retry composer self-update
 
 install:
   - travis_retry composer install $COMPOSER_ARGS --ignore-platform-reqs