Allow failures for 5.6

Author: Jakub Piasecki

.travis.yml

@@ -16,6 +16,10 @@ env:
     - RELEASE=stable COMPOSER_CHANNEL=snapshot
 
 matrix:
+  allow_failures:
+    # 5.6 is no longer supported by drupal-composer/drupal-project
+    - php: 5.6
+      env: RELEASE=stable COMPOSER_CHANNEL=stable
   exclude:
     - php: 5.6
       env: RELEASE=dev COMPOSER_CHANNEL=stable