Bump nokogiri in /pkg/mod/github.com/hashicorp/serf@v0.8.2/website

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.8.1 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/v1.8.1...v1.13.9)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...
Signed-off-by: Ndependabot[bot] <support@github.com>

pkg/mod/github.com/hashicorp/serf@v0.8.2/website/Gemfile.lock

@@ -101,17 +101,19 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
-    mini_portile2 (2.3.0)
+    mini_portile2 (2.8.0)
     minitest (5.10.3)
     multi_json (1.12.2)
-    nokogiri (1.8.1)
-      mini_portile2 (~> 2.3.0)
+    nokogiri (1.13.9)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     padrino-helpers (0.12.8.1)
       i18n (~> 0.6, >= 0.6.7)
       padrino-support (= 0.12.8.1)
       tilt (~> 1.4.1)
     padrino-support (0.12.8.1)
       activesupport (>= 3.1)
+    racc (1.6.0)
     rack (1.6.8)
     rack-livereload (0.3.16)
       rack