gem: add Ruby 3.3 support, drop Ruby 2.7 due to EOL

.github/workflows/ci.yml

@@ -16,10 +16,10 @@ jobs:
     strategy:
       matrix:
         ruby-version:
-        - '2.7'
         - '3.0'
         - '3.1'
         - '3.2'
+        - '3.3'
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby ${{ matrix.ruby-version }}

.rubocop.yml

@@ -3,7 +3,7 @@ require:
 - rubocop-rspec
 
 AllCops:
-  TargetRubyVersion: '2.7'
+  TargetRubyVersion: 3.0'
   NewCops: enable
 
 Gemspec/DevelopmentDependencies:

openvpn-status-web.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |s|
   s.executables = ['openvpn-status-web']
   s.extra_rdoc_files = Dir['README.md', 'LICENSE']
 
-  s.required_ruby_version = '>= 2.7'
+  s.required_ruby_version = '>= 3.0'
 
   s.add_runtime_dependency 'metriks'
   s.add_runtime_dependency 'rack', '~> 3.0'