build(deps): bump nokogiri from 1.12.5 to 1.13.8 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.12.5 to 1.13.8.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.12.5...v1.13.8)

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

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

Author: dependabot[bot]

docs/Gemfile.lock

@@ -205,23 +205,23 @@ GEM
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    mini_portile2 (2.6.1)
+    mini_portile2 (2.8.0)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.4)
     multipart-post (2.1.1)
-    nokogiri (1.12.5)
-      mini_portile2 (~> 2.6.1)
+    nokogiri (1.13.8)
+      mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     octokit (4.20.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.6)
-    racc (1.5.2)
+    racc (1.6.0)
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)