Quote-less `href` values are truncated

[charliermarsh]

If you open this page (https://iree.dev/pip-release-links.html), you'll see nodes like:

<a href=https://github.com/iree-org/iree/releases/download/candidate-20240814.985/iree-dist-20240814.985-linux-x86_64.tar.xz>iree-dist-20240814.985-linux-x86_64.tar.xz</a><br />

But when quotes are omitted, parse_attribute stops at the first / (presumedly to identify self-closing tags like />?), so the value gets truncate to https:.