qa: fix .travis.yaml

closes #24

Signed-off-by: Dmitriy Bespalov <dbespalov.rosko@gmail.com>

.travis.yml

@@ -44,15 +44,14 @@ matrix:
     - php: 7.2
       env:
         - DEPS=latest
-    -nightly:
-      - travis_retry composer install $COMPOSER_ARGS --ignore-platform-reqs
 
 before_install:
   - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi
   - pecl channel-update pecl.php.net
   - yes '' | pecl -q install -f $MONGO_DRIVER
 
 install:
+  - travis_retry composer install $COMPOSER_ARGS --ignore-platform-reqs
   - if [[ $LEGACY_DEPS != '' ]]; then travis_retry composer update $COMPOSER_ARGS --with-dependencies $LEGACY_DEPS ; fi
   - if [[ $DEPS == 'latest' ]]; then travis_retry composer update $COMPOSER_ARGS ; fi
   - if [[ $DEPS == 'lowest' ]]; then travis_retry composer update --prefer-lowest --prefer-stable $COMPOSER_ARGS ; fi