Update devDependencies and gems. (#25192)

Gemfile.lock

@@ -4,19 +4,30 @@ GEM
     addressable (2.5.2)
       public_suffix (>= 2.0.2, < 4.0)
     colorator (1.1.0)
+    concurrent-ruby (1.0.5)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.5)
+    eventmachine (1.2.5-x64-mingw32)
     ffi (1.9.18)
     ffi (1.9.18-x64-mingw32)
     forwardable-extended (2.6.0)
-    jekyll (3.6.2)
+    http_parser.rb (0.6.0)
+    i18n (0.9.1)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.7.0)
       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-redirect-from (0.13.0)
       jekyll (~> 3.3)
@@ -26,7 +37,7 @@ GEM
       jekyll (~> 3.3)
     jekyll-toc (0.5.1)
       nokogiri (~> 1.6)
-    jekyll-watch (1.5.1)
+    jekyll-watch (2.0.0)
       listen (~> 3.0)
     kramdown (1.16.2)
     liquid (4.0.0)
@@ -46,10 +57,10 @@ GEM
     rb-fsevent (0.10.2)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
-    rouge (2.2.1)
+    rouge (3.1.0)
     ruby_dep (1.5.0)
     safe_yaml (1.0.4)
-    sass (3.5.4)
+    sass (3.5.5)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -60,7 +71,7 @@ PLATFORMS
   x64-mingw32
 
 DEPENDENCIES
-  jekyll (~> 3.6.2)
+  jekyll (~> 3.7.0)
   jekyll-redirect-from (~> 0.13.0)
   jekyll-sitemap (~> 1.1.1)
   jekyll-toc (~> 0.5.1)