Build on PHP nightly

Author: scheb

.travis.yml

@@ -19,12 +19,16 @@ script:
   - ./bin/phpunit
 
 jobs:
+  fast_finish: true
+  allow_failures:
+    - php: nightly
   include:
     # Tests
     - php: 7.1
     - php: 7.2
     - php: 7.3
     - php: 7.4
+    - php: nightly
     - php: 7.1
       env:
           - COMPOSER_FLAGS="--prefer-lowest"