Bump nokogiri from 1.15.4 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.15.4 to 1.15.6.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.15.4...v1.15.6)

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

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

Gemfile.lock

@@ -110,21 +110,21 @@ GEM
     memoist (0.16.2)
     method_source (1.0.0)
     mini_mime (1.1.2)
-    mini_portile2 (2.8.5)
+    mini_portile2 (2.8.6)
     minitest (5.15.0)
     minitest-stub-const (0.6)
     mocha (1.11.2)
     multi_json (1.15.0)
     multipart-post (2.1.1)
-    nokogiri (1.15.4)
+    nokogiri (1.15.6)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     os (1.1.4)
     parallel (1.22.1)
     parser (3.1.2.0)
       ast (~> 2.4.1)
     public_suffix (4.0.6)
-    racc (1.7.1)
+    racc (1.7.3)
     rack (2.2.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)