Fix passing in content disposition type value

Author: stevebauman

src/Message.php

@@ -281,7 +281,7 @@ protected function getLazyAttachments(): array
                 $part->filename(),
                 $part->id(),
                 $part->contentType(),
-                $part->disposition()?->type(),
+                $part->disposition()?->type()?->value,
                 new Support\LazyBodyPartStream($this, $part),
             ),
             $this->bodyStructure()?->attachments() ?? []