Bump plek from 5.2.0 to 5.2.1

Bumps [plek](https://github.com/alphagov/plek) from 5.2.0 to 5.2.1.
- [Changelog](https://github.com/alphagov/plek/blob/main/CHANGELOG.md)
- [Commits](alphagov/plek@v5.2.0...v5.2.1)

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

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

Gemfile.lock

@@ -535,7 +535,7 @@ GEM
       racc
     parslet (2.0.0)
     pg (1.5.9)
-    plek (5.2.0)
+    plek (5.2.1)
     pp (0.6.2)
       prettyprint
     prettyprint (0.2.0)