Fixing PHP 5.6 compatibility, adding 7.1 tests

Author: Julien Neuhart

.travis.yml

@@ -3,6 +3,7 @@ language: php
 php:
  - 5.6
  - 7.0
+ - 7.1
 
 before_script:
  - composer install --no-interaction

src/SQLParser/Node/Expression.php

@@ -154,7 +154,7 @@ public function setBrackets($brackets)
     /**
      * @return string
      */
-    public function getDelimiter(): string
+    public function getDelimiter()
     {
         return $this->delimiter;
     }