Bump reffy from 15.2.1 to 16.0.0

Bumps [reffy](https://github.com/w3c/reffy) from 15.2.1 to 16.0.0.
- [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:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -41,7 +41,7 @@
     "gray-matter": "^4.0.3",
     "node-fetch": "^2.6.5",
     "node-pandoc": "0.3.0",
-    "reffy": "^15.0.0",
+    "reffy": "^16.0.0",
     "semver": "^7.3.5",
     "webidl2": "^24.2.2"
   },