Bump jekyll from 3.9.0 to 3.9.4

Bumps [jekyll](https://github.com/jekyll/jekyll) from 3.9.0 to 3.9.4.
- [Release notes](https://github.com/jekyll/jekyll/releases)
- [Changelog](https://github.com/jekyll/jekyll/blob/master/History.markdown)
- [Commits](jekyll/jekyll@v3.9.0...v3.9.4)

---
updated-dependencies:
- dependency-name: jekyll
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -33,13 +33,13 @@ GEM
     forwardable-extended (2.6.0)
     http_parser.rb (0.8.0)
     httpclient (2.8.3)
-    i18n (0.9.5)
+    i18n (1.14.1)
       concurrent-ruby (~> 1.0)
-    jekyll (3.9.0)
+    jekyll (3.9.4)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
-      i18n (~> 0.7)
+      i18n (>= 0.7, < 2)
       jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
       kramdown (>= 1.17, < 3)