Bump rdf from 3.2.11 to 3.2.12 (#479)

Bumps [rdf](https://github.com/ruby-rdf/rdf) from 3.2.11 to 3.2.12.
- [Release notes](https://github.com/ruby-rdf/rdf/releases)
- [Commits](ruby-rdf/rdf@3.2.11...3.2.12)

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

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

Gemfile.lock

@@ -136,7 +136,7 @@ GEM
     rainbow (3.1.1)
     rake (13.0.6)
     rchardet (1.8.0)
-    rdf (3.2.11)
+    rdf (3.2.12)
       link_header (~> 0.0, >= 0.0.8)
     rdf-aggregate-repo (3.2.1)
       rdf (~> 3.2)