Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/symfony/finder/Comparator/DateComparator.php

@@ -23,7 +23,7 @@ class DateComparator extends Comparator
      *
      * @throws \InvalidArgumentException If the test is not understood
      */
-    public function __construct($test)
+    public function __construct(string $test)
     {
         if (!preg_match('#^\s*(==|!=|[<>]=?|after|since|before|until)?\s*(.+?)\s*$#i', $test, $matches)) {
             throw new \InvalidArgumentException(sprintf('Don\'t understand "%s" as a date test.', $test));