build(deps): bump nokogiri in /appengine/rails-cloudsql-mysql (#1584)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.16.5 to 1.18.9.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.16.5...v1.18.9)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.18.9
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

appengine/rails-cloudsql-mysql/Gemfile.lock

@@ -203,7 +203,7 @@ GEM
     marcel (1.0.2)
     matrix (0.4.2)
     mini_mime (1.1.5)
-    mini_portile2 (2.8.7)
+    mini_portile2 (2.8.9)
     minitest (5.23.1)
     multi_json (1.15.0)
     mutex_m (0.2.0)
@@ -218,7 +218,7 @@ GEM
     net-smtp (0.3.3)
       net-protocol
     nio4r (2.5.9)
-    nokogiri (1.16.5)
+    nokogiri (1.18.9)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     os (1.1.4)
@@ -227,7 +227,7 @@ GEM
     public_suffix (5.0.3)
     puma (6.3.1)
       nio4r (~> 2.0)
-    racc (1.8.0)
+    racc (1.8.1)
     rack (3.0.12)
     rack-session (2.0.0)
       rack (>= 3.0.0)