fix: drop Ruby 3.1

Author: ninoseki

.github/workflows/ruby.yml

@@ -35,7 +35,7 @@ jobs:
           --health-retries=3
     strategy:
       matrix:
-        ruby: [3.1, 3.2, 3.3]
+        ruby: [3.2, 3.3]
     steps:
       - uses: actions/checkout@v4
       - name: Set up Ruby
@@ -49,10 +49,8 @@ jobs:
       - name: Test with PostgreSQL
         env:
           MITERU_DATABASE: postgresql://postgres:postgres@localhost:5432/test
-        run: |
-          bundle exec rake
+        run: bundle exec rake
       - name: Test with MySQL
         env:
           MITERU_DATABASE: mysql2://mysql:[email protected]:3306/test
-        run: |
-          bundle exec rake
+        run: bundle exec rake

miteru.gemspec

@@ -16,6 +16,8 @@ Gem::Specification.new do |spec|
   spec.homepage = "https://github.com/ninoseki/miteru"
   spec.license = "MIT"
 
+  spec.required_ruby_version = ">= 3.2"
+
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files = Dir.chdir(File.expand_path(__dir__)) do