Drop Ruby 2.6 and 2.7 support

.github/workflows/ci.yml

@@ -18,10 +18,10 @@ jobs:
     - uses: actions/checkout@v4
       with:
         ref: ${{ github.event.pull_request.head.sha }}
-    - name: Set up Ruby 2.6
+    - name: Set up Ruby 3.0
       uses: ruby/setup-ruby@master
       with:
-        ruby-version: '2.6'
+        ruby-version: '3.0'
         bundler-cache: true
     - name: Install dependencies
       run: bundle install --path=vendor/bundle --jobs 4 --retry 3
@@ -35,7 +35,7 @@ jobs:
     timeout-minutes: 20
     strategy:
       matrix:
-        ruby-version: ['2.6', '2.7', '3.0', '3.1', '3.2', '3.3']
+        ruby-version: ['3.0', '3.1', '3.2', '3.3']
         imagemagick-version:
           - { full: 7.1.1-29, major-minor: '7.1' }
     name: Ruby ${{ matrix.ruby-version }}

.rubocop.yml

@@ -5,7 +5,7 @@ require:
 
 AllCops:
     EnabledByDefault: true
-    TargetRubyVersion: 2.6
+    TargetRubyVersion: 3.0
     Exclude:
         - 'vendor/bundle/**/*'
         - 'rails_generators/gruff/**/*'

Dockerfile

@@ -5,7 +5,7 @@ RUN apt update && \
     apt install -y make gcc git bzip2 wget zlib1g-dev libgdbm-dev libreadline-dev libffi-dev
 
 RUN git clone --depth 1 https://github.com/rbenv/ruby-build.git && \
-    cd ruby-build/bin && ./ruby-build 2.6.10 /usr/local
+    cd ruby-build/bin && ./ruby-build 3.0.6 /usr/local
 
 RUN mkdir /tmp/gruff
 WORKDIR /tmp/gruff
@@ -17,7 +17,7 @@ ADD before_install_linux.sh /tmp/gruff/before_install_linux.sh
 ENV IMAGEMAGICK_VERSION 7.1.1-29
 RUN bash /tmp/gruff/before_install_linux.sh && \
     rm -rf /var/lib/apt/lists/* && \
-    gem install bundler:2.4.22 && \
+    gem install bundler:2.5.7 && \
     bundle install
 
 WORKDIR /opt/gruff

gruff.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
     s.add_development_dependency 'rubocop-rake', '~> 0.6.0'
   end
   s.add_dependency 'histogram'
-  s.required_ruby_version = '>= 2.6.0'
+  s.required_ruby_version = '>= 3.0.0'
 
   s.add_development_dependency 'rake'
   s.add_development_dependency 'minitest-reporters'