GHSA-9wjq-cp2p-hrgf: Loofah: SVG `href` attribute bypasses local-reference restriction

Loofah’s HTML5 sanitizer restricted only the xlink:href attribute on certain SVG elements to local, same-document references. Browsers also accept a plain href attribute as an alternative to the deprecated xlink:href per the SVG 2 spec, but Loofah did not apply the same restriction to it, allowing those elements to reference arbitrary external documents.