chore: Update travis config file

Signed-off-by: Bruno Gaspar <brunofgaspar1@gmail.com>

Author: brunogaspar

.travis.yml

@@ -3,17 +3,17 @@ language: php
 php:
   - 7.2
   - 7.3
+  - 7.4
 
 cache:
   directories:
     - $HOME/.composer/cache
 
 before_install:
   - composer config -g github-oauth.github.com $CI_USER_TOKEN
-  - travis_retry composer self-update
 
 install:
-  - travis_retry composer install --no-interaction --prefer-dist
+  - travis_retry composer install
 
 script:
-  - vendor/bin/phpunit --verbose
+  - vendor/bin/phpunit