query with problematic default namespace declaration

gistfile1.txt

xquery version "3.0";
declare namespace sitemap="http://www.sitemaps.org/schemas/sitemap/0.9";

(:
*********** Get data from GitHub *********
:)
let $textOrganisms := http:send-request(<http:request method='get' href='https://raw.githubusercontent.com/baskaufs/Bioimages/master/organisms.csv'/>)[2]
let $xmlOrganisms := csv:parse($textOrganisms, map { 'header' : true(),'separator' : "|" })

(:
*********** Main query *********
:)

return (



        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">{
          for $org in $xmlOrganisms//record
          order by $org/dcterms_modified descending
          return (
                 <url>
                   <loc>{$org/dcterms_identifier/text()}</loc>
                   <lastmod>{$org/dcterms_modified/text()}</lastmod>
                 </url>
                 )
        }</urlset>
         

)

Try this

xquery version "3.0";
declare default element namespace "http://www.sitemaps.org/schemas/sitemap/0.9";

(:
*********** Get data from GitHub *********
:)
let $textOrganisms := http:send-request(<http:request method='get' href='https://raw.githubusercontent.com/baskaufs/Bioimages/master/organisms.csv'/>)[2]
let $xmlOrganisms := csv:parse($textOrganisms, map { 'header' : true(),'separator' : "|" })
return 
(:
*********** Main query *********
:) 
(
        <urlset>{
          for $org in $xmlOrganisms//*:record
          order by $org/*:dcterms_modified descending
          return (
                 <url>
                   <loc>{$org/*:dcterms_identifier/text()}</loc>
                   <lastmod>{$org/*:dcterms_modified/text()}</lastmod>
                 </url>
                 )
        }</urlset>
)