fix declaration

Author: sokil

.travis.yml

@@ -5,15 +5,10 @@ dist: trusty
 language: php
 
 php:
-  - nightly
   - 7.3
   - 7.2
   - 7.1
 
-matrix:
-  allow_failures:
-    - php: nightly
-
 before_script:
   - composer install --no-interaction