Kanboard requires at least PHP 5.6 now

vendor/symfony/console/Helper/TableCell.php

@@ -18,14 +18,7 @@ use Symfony\Component\Console\Exception\InvalidArgumentException;
  */
 class TableCell
 {
-    /**
-     * @var string
-     */
     private $value;
-
-    /**
-     * @var array
-     */
     private $options = array(
         'rowspan' => 1,
         'colspan' => 1,
@@ -37,6 +30,10 @@ class TableCell
      */
     public function __construct($value = '', array $options = array())
     {
+        if (is_numeric($value) && !is_string($value)) {
+            $value = (string) $value;
+        }
+
         $this->value = $value;
 
         // check option names