fix error

I have some error after update `Cannot access property Jenssegers\Date\Date::$lastErrors` on `Date::createFromFormat('d.m.Y', $date)`, after re-init property to protected it was fixed.

src/Date.php

@@ -24,6 +24,13 @@ class Date extends Carbon
      */
     protected static $fallbackLocale = 'en';
 
+    /**
+     * The errors that can occur.
+     *
+     * @var array
+     */
+    protected static $lastErrors;
+
     /**
      * Returns new DateTime object.
      *