Bump rdf-ext from 1.3.5 to 2.5.2

Bumps [rdf-ext](https://github.com/rdf-ext/rdf-ext) from 1.3.5 to 2.5.2.
- [Commits](rdf-ext/rdf-ext@v1.3.5...v2.5.2)

---
updated-dependencies:
- dependency-name: rdf-ext
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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