Support Ruby 3 / Drop Jekyll v3.8 / Drop Ruby v2.4 (#140)

* Use ruby/setup-ruby

* Drop jekyll 3.8

* Add Ruby 3.0

* Drop Ruby 2.4

* rubocop x Ruby3

* coverage x Ruby3

* v0.17.0

.github/workflows/ci.yml

@@ -4,27 +4,19 @@ jobs:
   build:
     strategy:
       matrix:
-        ruby: [2.4, 2.5, 2.6, 2.7]
+        ruby: [2.5, 2.6, 2.7, 3.0]
         gemfile:
-          - gemfiles/jekyll_3.8.gemfile
           - gemfiles/jekyll_3.9.gemfile
           - gemfiles/jekyll_4.0.gemfile
           - gemfiles/jekyll_4.1.gemfile
           - gemfiles/jekyll_4.2.gemfile
-        exclude:
-        - ruby: 2.4
-          gemfile: gemfiles/jekyll_4.0.gemfile
-        - ruby: 2.4
-          gemfile: gemfiles/jekyll_4.1.gemfile
-        - ruby: 2.4
-          gemfile: gemfiles/jekyll_4.2.gemfile
     env:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby ${{ matrix.ruby }}
-      uses: actions/setup-ruby@v1
+      uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
     - name: bundle install

.github/workflows/coverage.yml

@@ -4,13 +4,13 @@ jobs:
   build:
     strategy:
       matrix:
-        ruby: [2.7]
+        ruby: [3.0]
     runs-on: ubuntu-latest
     name: coverage
     steps:
       - uses: actions/checkout@v2
       - name: Set up Ruby ${{ matrix.ruby }}
-        uses: actions/setup-ruby@v1
+        uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
       - name: bundle install

.github/workflows/rubocop.yml

@@ -4,13 +4,13 @@ jobs:
   build:
     strategy:
       matrix:
-        ruby: [2.7]
+        ruby: [3.0]
     runs-on: ubuntu-latest
     name: rubocop
     steps:
       - uses: actions/checkout@v2
       - name: Set up Ruby ${{ matrix.ruby }}
-        uses: actions/setup-ruby@v1
+        uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
       - name: bundle install

jekyll-toc.gemspec

@@ -19,6 +19,6 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.4'
 
-  spec.add_dependency 'jekyll', '>= 3.8'
+  spec.add_dependency 'jekyll', '>= 3.9'
   spec.add_dependency 'nokogiri', '~> 1.10'
 end

lib/table_of_contents/version.rb

@@ -2,6 +2,6 @@
 
 module Jekyll
   module TableOfContents
-    VERSION = '0.16.1'
+    VERSION = '0.17.0'
   end
 end