Update clean-css

[kleisauke]

Currently, one- and two-letter CSS property names do not appear in the minified CSS output because cdnjs uses an outdated version of clean-css (v3.3.10). For example, with Mocha, this results in a non-functional progress indicator because it strips some essential SVG properties:

@@ -377,9 +377,6 @@ body {
 #mocha-stats :is(.ring-flatlight, .ring-highlight) {
   --stroke-thickness: 1.65px;
   --center: calc(var(--ring-container-size) / 2);
-  cx: var(--center);
-  cy: var(--center);
-  r: calc(var(--ring-radius) - calc(var(--stroke-thickness) / 2));
   fill: hsla(0, 0%, 0%, 0);
   stroke-width: var(--stroke-thickness);
 }

(see: https://cdnjs.cloudflare.com/ajax/libs/mocha/10.6.0/mocha.min.css)

This was fixed with commit clean-css/clean-css@0ffb65d.