Bump rdf-normalize from 0.5.0 to 0.5.1

Bumps [rdf-normalize](https://github.com/ruby-rdf/rdf-normalize) from 0.5.0 to 0.5.1.
- [Release notes](https://github.com/ruby-rdf/rdf-normalize/releases)
- [Commits](https://github.com/ruby-rdf/rdf-normalize/compare/0.5.0...0.5.1)

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

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

Gemfile.lock

@@ -538,7 +538,7 @@ GEM
     random_name_generator (2.0.1)
     rdf (3.2.9)
       link_header (~> 0.0, >= 0.0.8)
-    rdf-normalize (0.5.0)
+    rdf-normalize (0.5.1)
       rdf (~> 3.2)
     redcarpet (3.5.1)
     redis (4.5.1)