.travis.yml remove deprecated switch

Author: ek9

.travis.yml

@@ -13,7 +13,7 @@ matrix:
 
 before_script:
   - composer validate
-  - if [[ $deps = low ]]; then composer update --prefer-lowest --prefer-stable; else composer update --dev; fi
+  - if [[ $deps = low ]]; then composer update --prefer-lowest --prefer-stable; else composer update; fi
 
 script: ./bin/phpunit -vvv