Improve travis config

Author: snapshotpl

.travis.yml

@@ -6,12 +6,13 @@ matrix:
     - php: 5.5
     - php: 5.6
     - php: 7
+    - php: 7.1
     - php: hhvm
   allow_failures:
     - php: hhvm
 
 install:
-  - travis_retry composer install --no-interaction --ignore-platform-reqs --prefer-source
+  - travis_retry composer install --no-interaction --prefer-source
   - composer info -i
 
 script: