Bump nokogiri from 1.12.5 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.12.5 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@v1.12.5...v1.15.6)

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

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

Gemfile.lock

@@ -132,17 +132,17 @@ GEM
       mini_mime (>= 0.1.1)
     method_source (0.9.2)
     mini_mime (1.0.2)
-    mini_portile2 (2.8.0)
+    mini_portile2 (2.8.6)
     minitest (5.17.0)
     nio4r (2.7.1)
-    nokogiri (1.13.10)
-      mini_portile2 (~> 2.8.0)
+    nokogiri (1.15.6)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     pg (1.2.0)
     public_suffix (4.0.6)
     puma (5.6.8)
       nio4r (~> 2.0)
-    racc (1.6.1)
+    racc (1.7.3)
     rack (2.2.9)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)