Increase php memory for composer with php 5.6

Author: Jeremiah VALERIE

.travis.yml

@@ -32,7 +32,7 @@ jobs:
     include:
         - stage: Test
           php: 5.6
-          env: COMPOSER_UPDATE_FLAGS=--prefer-lowest SYMFONY_DEPRECATIONS_HELPER=disabled GRAPHQLPHP_VERSION=^0.11.2
+          env: COMPOSER_MEMORY_LIMIT=-1 COMPOSER_UPDATE_FLAGS=--prefer-lowest SYMFONY_DEPRECATIONS_HELPER=disabled GRAPHQLPHP_VERSION=^0.11.2
         - php: 5.6
           env: SYMFONY_VERSION=3.1.* SYMFONY_DEPRECATIONS_HELPER=disabled GRAPHQLPHP_VERSION=0.12
         - php: 7.0