Fix for #155 Use a plain DateTime object for the value of the {attach…

…ment}_updated_at field.

src/Attachment.php

@@ -9,6 +9,7 @@
 use Codesleeve\Stapler\ORM\StaplerableInterface;
 use Codesleeve\Stapler\Factories\File as FileFactory;
 use JsonSerializable;
+use DateTime;
 
 class Attachment implements AttachmentInterface, JsonSerializable
 {
@@ -131,7 +132,7 @@ public function setUploadedFile($uploadedFile)
         $this->instanceWrite('file_name', $this->uploadedFile->getFilename());
         $this->instanceWrite('file_size', $this->uploadedFile->getSize());
         $this->instanceWrite('content_type', $this->uploadedFile->getMimeType());
-        $this->instanceWrite('updated_at', date('Y-m-d H:i:s'));
+        $this->instanceWrite('updated_at', new DateTime);
         $this->queueAllForWrite();
     }