fix: Ignore HTML errors when creating tickets from emails

I had an error because an email contained a tag `<o:p>` (the `o`
namespace wasn't defined). The fetching was failing quite badly because
of this error.

I think we should just ignore this kind of errors as they are produced
by bad HTML. It should be ok since we sanitize the HTML later.

src/MessageHandler/CreateTicketsFromMailboxEmailsHandler.php

@@ -251,7 +251,7 @@ private function replaceAttachmentsUrls(string $content, array $messageDocuments
             'UTF-8'
         );
 
-        $contentDom->loadHTML($content);
+        $contentDom->loadHTML($content, \LIBXML_NOERROR);
         $contentDomXPath = new \DomXPath($contentDom);
 
         foreach ($messageDocuments as $attachmentId => $messageDocument) {