Remove duplicate entry

Author: B-Galati

.travis.yml

@@ -24,7 +24,6 @@ matrix:
       env: SYMFONY_VERSION="2.8.*"
     - php: 5.6
       env: SYMFONY_VERSION="3.4.*" DEPENDENCIES=dev
-    - php: 7.1
     - php: 7.0
     - php: 7.1
     - php: 7.2