Bump nokogiri from 1.18.4 to 1.18.8

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.18.4 to 1.18.8.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.18.4...v1.18.8)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.18.8
  dependency-type: indirect
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -111,7 +111,7 @@ GEM
       net-protocol
     netrc (0.11.0)
     nio4r (2.7.4)
-    nokogiri (1.18.4-x86_64-linux-gnu)
+    nokogiri (1.18.8-x86_64-linux-gnu)
       racc (~> 1.4)
     otr-activerecord (2.5.0)
       activerecord (>= 6.0, < 8.1)