Bump nokogiri from 1.13.8 to 1.13.9 in /gentest

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.13.8 to 1.13.9.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sparklemotion/nokogiri/compare/v1.13.8...v1.13.9)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...

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

gentest/Gemfile.lock

@@ -3,7 +3,7 @@ GEM
   specs:
     childprocess (4.1.0)
     mini_portile2 (2.8.0)
-    nokogiri (1.13.8)
+    nokogiri (1.13.9)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     racc (1.6.0)