Sending a request with XML data

I would try something like this:

const xmlBody = `<?xml version="1.0"?>
<catalog>
   <book id="bk101">
      <author>John Doe</author>
      <title>Postman Developer's Guide</title>
      <genre>Computer</genre>
      <price>44.95</price>
      <publish_date>2019-10-01</publish_date>
      <description>An in-depth look at creating APIs 
      with Postman.</description>
   </book>
</catalog>`;

const options = {
  'method': 'POST',
  'url': 'httpbin.org/post',
  'header': {
    'Content-Type': 'application/xml'
  },
  body: xmlBody

}
pm.sendRequest(options, function (error, response) { 
  if (error) throw new Error(error);
  console.log(response.body);
});

Does this help?