build(deps-dev): bump nokogiri in /appengine/static_files/sinatra (#1544)

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.16.5 to 1.18.3.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/v1.18.3/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.16.5...v1.18.3)

---
updated-dependencies:
- dependency-name: nokogiri
  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/static_files/sinatra/Gemfile.lock

@@ -24,17 +24,17 @@ GEM
       websocket-driver (>= 0.6, < 0.8)
     matrix (0.4.2)
     mini_mime (1.1.5)
-    mini_portile2 (2.8.6)
+    mini_portile2 (2.8.8)
     mustermann (3.0.0)
       ruby2_keywords (~> 0.0.1)
     nio4r (2.7.0)
-    nokogiri (1.16.5)
+    nokogiri (1.18.3)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     public_suffix (5.0.3)
     puma (6.4.2)
       nio4r (~> 2.0)
-    racc (1.7.3)
+    racc (1.8.1)
     rack (2.2.8.1)
     rack-protection (3.1.0)
       rack (~> 2.2, >= 2.2.4)