fix: update for recent changelog format change (#576)

The Node.js `CHANGELOG.md` has replaced use of `<sup>` tags.

Refs: nodejs/node#40475

lib/prepare_release.js

@@ -345,7 +345,7 @@ class ReleasePreparation {
           const eolDate = getEOLDate(date);
           const eol = eolDate.toISOString().split('-').slice(0, 2).join('-');
           arr[idx] = arr[idx].replace('"Current"', `"LTS Until ${eol}"`);
-          arr[idx] = arr[idx].replace('<sup>Current</sup>', '<sup>LTS</sup>');
+          arr[idx] = arr[idx].replace('(Current)', '(LTS)');
         } else if (arr[idx].includes('**Long Term Support**')) {
           arr[idx] = arr[idx].replace(
             '**Long Term Support**',