This is the format of my sitemap.xml
<?xml version="1.0" encoding="UTF-8"?>
<urlset
xmlns="https://www.sitemaps.org/schemas/sitemap/0.9"
xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xmlns:xhtml="https://www.w3.org/1999/xhtml"
xsi:schemaLocation="https://www.sitemaps.org/schemas/sitemap/0.9
https://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
<url>
<loc>https://example.com</loc>
<xhtml:link
rel="alternate"
hreflang="en-us"
href="https://example.com" />
<xhtml:link
rel="alternate"
hreflang="en-gb"
href="https://example.com/uk/" />
<xhtml:link
rel="alternate"
hreflang="x-default"
href="https://example.com" />
</url>
</urlset>
However, search console keeps giving me the error that it has an incorrect namespace on Line 10.
I have also tried the solution available here: XSD For Sitemap with HREFLANG
But I get the same error on that. What am I doing wrong?