update CI ruby to 2.7

.github/workflows/ci.yml

@@ -1,10 +1,3 @@
-# This workflow uses actions that are not certified by GitHub.
-# They are provided by a third-party and are governed by
-# separate terms of service, privacy policy, and support
-# documentation.
-# This workflow will download a prebuilt Ruby version, install dependencies and run tests with Rake
-# For more information see: https://github.com/marketplace/actions/setup-ruby-jruby-and-truffleruby
-
 name: Ruby
 
 on:
@@ -20,16 +13,11 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         ruby:
-          # - 2.5
-          # - 2.6
           - '2.7'
           - '3.0'
           - '3.1'
           - '3.2'
           - '3.3'
-        # include:
-        #   - os: macos-13
-        #     ruby: 2.5
     name: Ruby ${{ matrix.ruby }} test (${{ matrix.os }})
     steps:
     - uses: actions/checkout@v4
@@ -60,6 +48,6 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.5
+          ruby-version: 2.7
           bundler-cache: true
       - run: bin/test/${{ matrix.repo }}