Bump nokogiri from 1.13.8 to 1.15.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.13.8 to 1.15.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.13.8...v1.15.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -231,22 +231,22 @@ GEM
       nokogiri (>= 1.5.9)
     mercenary (0.3.6)
     method_source (1.0.0)
-    mini_portile2 (2.8.0)
+    mini_portile2 (2.8.5)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.16.2)
-    nokogiri (1.13.8)
-      mini_portile2 (~> 2.8.0)
+    nokogiri (1.15.4)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     octokit (4.25.1)
       faraday (>= 1, < 3)
       sawyer (~> 0.9)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.7)
-    racc (1.6.0)
+    racc (1.7.3)
     rack (2.2.4)
     rack-test (2.0.2)
       rack (>= 1.3)