Bump nokogiri from 1.15.2 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.15.2 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@v1.15.2...v1.15.6)

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

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

Gemfile.lock

@@ -72,7 +72,7 @@ GEM
       net-pop
       net-smtp
     mini_mime (1.1.2)
-    mini_portile2 (2.8.2)
+    mini_portile2 (2.8.5)
     minitest (5.19.0)
     mutex_m (0.2.0)
     net-imap (0.3.4)
@@ -84,15 +84,15 @@ GEM
       timeout
     net-smtp (0.3.3)
       net-protocol
-    nokogiri (1.15.2)
+    nokogiri (1.15.6)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.15.2-x86_64-darwin)
+    nokogiri (1.15.6-x86_64-darwin)
       racc (~> 1.4)
     parallel (1.23.0)
     parser (3.2.2.1)
       ast (~> 2.4.1)
-    racc (1.7.1)
+    racc (1.7.3)
     rack (3.0.9.1)
     rack-session (2.0.0)
       rack (>= 3.0.0)