actualizar a jekyll 4 e instalar plugins

Gemfile

 source 'https://rubygems.org'
 
 gem 'jekyll'
+gem 'jekyll-seo-tag'
+gem 'jekyll-gzip'

Gemfile.lock

 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)
     colorator (1.1.0)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.5)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     eventmachine (1.2.7)
-    ffi (1.9.25)
+    ffi (1.11.1)
     forwardable-extended (2.6.0)
     http_parser.rb (0.6.0)
-    i18n (0.9.5)
+    i18n (1.6.0)
       concurrent-ruby (~> 1.0)
-    jekyll (3.8.4)
+    jekyll (4.0.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
-      i18n (~> 0.7)
-      jekyll-sass-converter (~> 1.0)
+      i18n (>= 0.9.5, < 2)
+      jekyll-sass-converter (~> 2.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 1.14)
+      kramdown (~> 2.1)
+      kramdown-parser-gfm (~> 1.0)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (>= 1.7, < 4)
+      rouge (~> 3.0)
       safe_yaml (~> 1.0)
-    jekyll-sass-converter (1.5.2)
-      sass (~> 3.4)
-    jekyll-watch (2.1.1)
+      terminal-table (~> 1.8)
+    jekyll-gzip (2.3.0)
+      jekyll (>= 3.0, < 5.0)
+    jekyll-sass-converter (2.0.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-seo-tag (2.6.1)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (1.17.0)
-    liquid (4.0.1)
+    kramdown (2.1.0)
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
     mercenary (0.3.6)
-    pathutil (0.16.1)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.0.3)
+    public_suffix (4.0.1)
     rb-fsevent (0.10.3)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
-    rouge (3.3.0)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
+    rouge (3.10.0)
     ruby_dep (1.5.0)
-    safe_yaml (1.0.4)
-    sass (3.6.0)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
+    safe_yaml (1.0.5)
+    sassc (2.2.0)
+      ffi (~> 1.9)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    unicode-display_width (1.6.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   jekyll
+  jekyll-gzip
+  jekyll-seo-tag
 
 BUNDLED WITH
-   1.16.3
+   2.0.2