Google requires an xmlns for PageMap

[AlexParamonov]

Hey there,

Thanks a lot for bringing sitemaps to elixir!
I was trying to generate a PageMap and validate it in the google search console but faced the infamous error message:

Incorrect namespace - Your Sitemap or Sitemap index file doesn't properly declare the namespace.

Parent tag:
url
Tag:
PageMap

In Google examples, they always use the xmlns tags for PageMaps, so I gave it a try and was able to import the sitemap after that.
Please find bellow the implementation of attaching the schema to the PageMap tag.

Cheers,
Alexander