Usa versões corretas do Ruby e bundler, e reseta Gemfile e Gemfile.lock

Gemfile

@@ -1,6 +1,7 @@
 source "https://rubygems.org"
 
 # Install github-pages gem (https://jekyllrb.com/docs/github-pages/)
+gem "github-pages", group: :jekyll_plugins
 
 # Plugins
 group :jekyll_plugins do
@@ -12,6 +13,3 @@ gem "tzinfo-data", platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 
 # Performance-booster for watching directories on Windows
 gem "wdm", "~> 0.1.0" if Gem.win_platform?
-
-
-gem "webrick", "~> 1.7"

Gemfile.lock

@@ -7,7 +7,7 @@ GEM
       minitest (~> 5.1)
       tzinfo (~> 1.1)
       zeitwerk (~> 2.2, >= 2.2.2)
-    addressable (2.8.0)
+    addressable (2.7.0)
       public_suffix (>= 2.0.2, < 5.0)
     coffee-script (2.4.1)
       coffee-script-source
@@ -29,7 +29,7 @@ GEM
     faraday (1.2.0)
       multipart-post (>= 1.2, < 3)
       ruby2_keywords
-    ffi (1.15.1)
+    ffi (1.14.2)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
     github-pages (209)
@@ -220,7 +220,7 @@ GEM
       forwardable-extended (~> 2.6)
     public_suffix (3.1.1)
     racc (1.5.2)
-    rb-fsevent (0.11.0)
+    rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)
@@ -251,7 +251,6 @@ GEM
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
-    webrick (1.7.0)
     zeitwerk (2.4.2)
 
 PLATFORMS
@@ -260,7 +259,6 @@ PLATFORMS
 DEPENDENCIES
   github-pages
   tzinfo-data
-  webrick (~> 1.7)
 
 BUNDLED WITH
-   2.2.19
+   2.0.1