Bump reffy from 15.0.2 to 15.2.0 (#1219)

Bumps [reffy](https://github.com/w3c/reffy) from 15.0.2 to 15.2.0.
- [Changelog](https://github.com/w3c/reffy/blob/main/CHANGELOG.md)
- [Commits](https://github.com/w3c/reffy/commits)

---
updated-dependencies:
- dependency-name: reffy
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package-lock.json

@@ -35,7 +35,7 @@
     "css-tree": "2.3.1",
     "flags": "0.1.3",
     "mocha": "10.4.0",
-    "reffy": "15.0.2",
+    "reffy": "15.2.0",
     "rimraf": "5.0.5",
     "strudy": "^2.2.0",
     "webidl2": "24.4.1"