Bump async from 2.6.1 to 2.6.4 in /utils/hsts-prune (#20197)

Bumps [async](https://github.com/caolan/async) from 2.6.1 to 2.6.4.
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/v2.6.4/CHANGELOG.md)
- [Commits](caolan/async@v2.6.1...v2.6.4)

---
updated-dependencies:
- dependency-name: async
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

utils/hsts-prune/package-lock.json

@@ -10,7 +10,7 @@
   "license": "GPL-3.0",
   "dependencies": {
     "JSONStream": "^1.3.0",
-    "async": "^2.1.4",
+    "async": "^2.6.4",
     "base64-stream": "^0.1.3",
     "escape-string-regexp": "^1.0.5",
     "highland": "^2.10.1",