Bump nokogiri from 1.13.6 to 1.15.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.13.6 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@v1.13.6...v1.15.4)

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

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

Gemfile.lock

@@ -180,7 +180,7 @@ GEM
     marcel (1.0.2)
     method_source (1.0.0)
     mini_mime (1.1.2)
-    mini_portile2 (2.8.0)
+    mini_portile2 (2.8.5)
     minitest (5.15.0)
     multipart-post (2.2.0)
     nenv (0.3.0)
@@ -199,8 +199,8 @@ GEM
       net-protocol
       timeout
     nio4r (2.5.8)
-    nokogiri (1.13.6)
-      mini_portile2 (~> 2.8.0)
+    nokogiri (1.15.4)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     notiffany (0.1.3)
       nenv (~> 0.1)
@@ -216,7 +216,7 @@ GEM
     puma (5.6.4)
       nio4r (~> 2.0)
     raabro (1.4.0)
-    racc (1.6.0)
+    racc (1.7.2)
     rack (2.2.3.1)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)