Bump jekyll from 3.6.2 to 3.8.7

Bumps [jekyll](https://github.com/jekyll/jekyll) from 3.6.2 to 3.8.7.
- [Release notes](https://github.com/jekyll/jekyll/releases)
- [Changelog](https://github.com/jekyll/jekyll/blob/master/History.markdown)
- [Commits](jekyll/jekyll@v3.6.2...v3.8.7)

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

Gemfile.lock

@@ -1,28 +1,38 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     babel-source (5.8.35)
     babel-transpiler (0.7.0)
       babel-source (>= 4.0, < 6)
       execjs (~> 2.0)
     colorator (1.1.0)
+    concurrent-ruby (1.1.6)
     cssminify2 (2.0.1)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
     execjs (2.7.0)
-    ffi (1.9.23)
+    ffi (1.12.2)
     forwardable-extended (2.6.0)
     htmlcompressor (0.4.0)
-    jekyll (3.6.2)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.8.7)
       addressable (~> 2.4)
       colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
-      jekyll-watch (~> 1.1)
+      jekyll-watch (~> 2.0)
       kramdown (~> 1.14)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (>= 1.7, < 3)
+      rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
     jekyll-babel (1.1.0)
       babel-transpiler
@@ -33,25 +43,23 @@ GEM
       uglifier (~> 3.2)
     jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-watch (1.5.1)
+    jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (1.16.2)
-    liquid (4.0.0)
-    listen (3.1.5)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-      ruby_dep (~> 1.2)
+    kramdown (1.17.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    pathutil (0.16.1)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (2.0.5)
-    rb-fsevent (0.10.3)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
-    rouge (2.2.1)
-    ruby_dep (1.5.0)
-    safe_yaml (1.0.4)
-    sass (3.5.5)
+    public_suffix (4.0.5)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rouge (3.19.0)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)