GHSA-x4fp-j954-r2f4: xmldom: End-tag Whitespace-Trim Regex ReDoS — quadratic backtracking in the 0.8.x end-tag parser

## Summary On the `@xmldom/xmldom` **`0.8.x`** line, parsing an XML end tag whose name is followed by a long run of whitespace and then a non-whitespace character triggers quadratic-time regular-expression backtracking (ReDoS), so a single small crafted end tag stalls the Node.js event loop. It is reachable from `DOMParser.parseFromString` under **default options**, unauthenticated, before any validity check — an availability-only denial of service. The `0.9.x` line is **not** affected. …