jekyll: 3.7.3 -> 3.8.0

And add an update script.

pkgs/applications/misc/jekyll/full/Gemfile.lock

@@ -22,7 +22,7 @@ GEM
       http_parser.rb (~> 0.6.0)
     eventmachine (1.2.5)
     execjs (2.7.0)
-    faraday (0.14.0)
+    faraday (0.15.0)
       multipart-post (>= 1.2, < 3)
     fast-stemmer (1.0.2)
     ffi (1.9.23)
@@ -34,7 +34,7 @@ GEM
     http_parser.rb (0.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.7.3)
+    jekyll (3.8.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -47,7 +47,7 @@ GEM
       pathutil (~> 0.9)
       rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-    jekyll-avatar (0.5.0)
+    jekyll-avatar (0.6.0)
       jekyll (~> 3.0)
     jekyll-coffeescript (1.1.1)
       coffee-script (~> 2.2)
@@ -56,7 +56,7 @@ GEM
       jekyll (~> 3.3)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-mentions (1.2.0)
+    jekyll-mentions (1.3.0)
       activesupport (~> 4.0)
       html-pipeline (~> 2.3)
       jekyll (~> 3.0)
@@ -101,16 +101,16 @@ GEM
     public_suffix (3.0.2)
     pygments.rb (1.2.1)
       multi_json (>= 1.0.0)
-    rb-fsevent (0.10.2)
+    rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
     rdiscount (2.2.0.1)
-    rdoc (6.0.1)
+    rdoc (6.0.3)
     redcarpet (3.4.0)
     rouge (3.1.1)
     ruby_dep (1.5.0)
     safe_yaml (1.0.4)
-    sass (3.5.5)
+    sass (3.5.6)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)