Bump nokogiri from 1.10.4 to 1.13.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.10.4 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@v1.10.4...v1.13.4)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -17,10 +17,12 @@ GEM
       safe_yaml (~> 1.0.0)
     diff-lcs (1.3)
     hashdiff (0.3.9)
-    mini_portile2 (2.4.0)
-    nokogiri (1.10.4)
-      mini_portile2 (~> 2.4.0)
+    mini_portile2 (2.8.0)
+    nokogiri (1.13.4)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     public_suffix (3.0.3)
+    racc (1.6.0)
     rake (12.3.0)
     rspec (3.7.0)
       rspec-core (~> 3.7.0)