Bump nokogiri from 1.15.5 to 1.15.6

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.15.5 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@v1.15.5...v1.15.6)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -97,7 +97,7 @@ GEM
     net-sftp (2.1.2)
       net-ssh (>= 2.6.5)
     net-ssh (4.2.0)
-    nokogiri (1.15.5)
+    nokogiri (1.15.6)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     padrino-helpers (0.12.9)