Upgrade to jekyll 3.9.1.

* Manually upgrade to jekyll 3.9.1.
* Add `kramdown-parser-gfm` which is now required.
* Run `bundle update`.

Author: sjrd

Gemfile

@@ -1,9 +1,10 @@
 source "https://rubygems.org"
 ruby '2.7.5'
 gem 'ruby_dep', '1.3.1'
-gem 'jekyll', '3.8.5'
+gem 'jekyll', '3.9.1'
 gem 'jekyll-paginate', '1.1.0'
 gem 'jekyll-assets', '2.1.2'
 gem 'sass', '3.4.20'
 gem 'execjs', '2.6.0'
 gem 'uglifier', '2.7.2'
+gem "kramdown-parser-gfm", "~> 1.1"

Gemfile.lock

@@ -19,14 +19,14 @@ GEM
     http_parser.rb (0.8.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.8.5)
+    jekyll (3.9.1)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
       i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 1.14)
+      kramdown (>= 1.17, < 3)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
@@ -44,7 +44,10 @@ GEM
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     json (2.6.1)
-    kramdown (1.17.0)
+    kramdown (2.3.1)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
     liquid (4.0.3)
     listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
@@ -57,6 +60,7 @@ GEM
     rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
+    rexml (3.2.5)
     rouge (3.28.0)
     ruby_dep (1.3.1)
     safe_yaml (1.0.5)
@@ -77,9 +81,10 @@ PLATFORMS
 
 DEPENDENCIES
   execjs (= 2.6.0)
-  jekyll (= 3.8.5)
+  jekyll (= 3.9.1)
   jekyll-assets (= 2.1.2)
   jekyll-paginate (= 1.1.0)
+  kramdown-parser-gfm (~> 1.1)
   ruby_dep (= 1.3.1)
   sass (= 3.4.20)
   uglifier (= 2.7.2)