Ignore deprecations on prefer-lowest too

Author: Jean85

.travis.yml

@@ -35,6 +35,8 @@ jobs:
   include:
     - name: Prefer lowest
       php: 7.1
+      env:
+        SYMFONY_DEPRECATIONS_HELPER: disabled
       install:
         - composer update --prefer-lowest --no-interaction --no-suggest --prefer-dist --prefer-stable
     - name: Code coverage