Improve `<meta>` tag `content` URL validation

[lkmgr]

The content attribute of a <meta> tag is assumed to be a URL if new URL(content) doesn't throw an error:

linkinator/src/links.ts

Lines 121 to 129 in 39ca01c

	// Only for <meta content=""> tags, only validate the url if
	// the content actually looks like a url
	if (tag === 'meta' && attributes.content) {
	try {
	new URL(attributes.content);
	} catch {
	return;
	}
	}

However, this may be too lenient as it leads to values that are not meant to be URLs to be treated as URLs, like the following:

<meta name="description" content="Test: Hello">