Bump nokogiri from 1.10.8 to 1.13.4 in /ruby

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.8 to 1.13.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/v1.13.4/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.10.8...v1.13.4)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: direct:production
...

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

Author: dependabot[bot]

ruby/Gemfile.lock

@@ -6,11 +6,13 @@ GEM
     faraday (0.15.4)
       multipart-post (>= 1.2, < 3)
     ipaddress (0.8.3)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.0)
     multipart-post (2.1.1)
-    nokogiri (1.10.8)
-      mini_portile2 (~> 2.4.0)
+    nokogiri (1.13.4)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     public_suffix (4.0.1)
+    racc (1.6.0)
 
 PLATFORMS
   ruby