[FIX] Missing state() function on Factory (#198)

* Add temporary function stub to prevent fatal

* Fix CI

Author: jakub-klapka

src/Testing/Factory.php

@@ -237,4 +237,14 @@ public function offsetUnset($offset)
     {
         unset($this->definitions[$offset]);
     }
+
+    /**
+     * Temporary fix to prevent Fatal on Laravel 5.3.17
+     *
+     * @return $this
+     */
+    public function state()
+    {
+        return $this;
+    }
 }