update to ruby 3.1

Author: Flyingmana

.docker/jekyll.dockerfile

@@ -1,4 +1,4 @@
-FROM ruby:2.5
+FROM ruby:3.1
 
 RUN apt-get update \
   && apt-get install -y \

.ruby-version

@@ -1 +1 @@
-2.5
+3.1

Gemfile

@@ -6,5 +6,7 @@ git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
 # gem "rails"
 
-gem "jekyll", "3.8.5"
+gem "jekyll", "3.9.3"
 gem "github-pages", group: :jekyll_plugins
+
+gem "webrick", "~> 1.8"