website_blog_rss: produces an invalid RSS feed

Created by: gurneyalex

Hello,

I installed website_blog_rss on the OCA instance and I get some xml at https://odoo-community.org/blog_rss.xml but there seem to be a problem as the generated RSS is not considered valid by the W3C rss feed validator, which causes several RSS parsers such as Thunderbird's to fail loading it