Bump nokogiri from 1.6.8.1 to 1.13.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.6.8.1 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@v1.6.8.1...v1.13.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -135,7 +135,7 @@ GEM
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
     mime-types (1.25.1)
-    mini_portile2 (2.1.0)
+    mini_portile2 (2.8.0)
     momentjs-rails (2.20.1)
       railties (>= 3.1)
     multi_json (1.13.1)
@@ -146,8 +146,9 @@ GEM
       net-ssh (>= 2.6.5)
     net-ssh (2.9.4)
     netrc (0.11.0)
-    nokogiri (1.6.8.1)
-      mini_portile2 (~> 2.1.0)
+    nokogiri (1.13.4)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     oauth2 (1.4.0)
       faraday (>= 0.8, < 0.13)
       jwt (~> 1.0)
@@ -158,6 +159,7 @@ GEM
     polyglot (0.3.5)
     power_assert (1.1.3)
     public_suffix (2.0.5)
+    racc (1.6.0)
     rack (1.4.7)
     rack-accept (0.4.5)
       rack (>= 0.4)