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] <[email protected]>

Author: dependabot[bot]

Gemfile.lock

@@ -526,7 +526,7 @@ GEM
     parser (3.3.7.0)
       ast (~> 2.4.1)
       racc
-    plek (5.2.0)
+    plek (5.2.1)
     pp (0.6.2)
       prettyprint
     prettyprint (0.2.0)