Allow tests to fail on PHP7.2

Author: jaylinski

.travis.yml

@@ -5,6 +5,10 @@ php:
   - 7.1
   - 7.2
 
+matrix:
+  allow_failures:
+    - php: 7.2
+
 before_script:
   - travis_retry composer install --prefer-source --no-interaction --dev