test ruby 3.4 on github actions

Author: flyerhzm

Diff for: .github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.7', '3.0', '3.1', '3.2', '3.3']
+        ruby-version: ['2.7', '3.0', '3.1', '3.2', '3.3', '3.4']
 
     steps:
     - uses: actions/checkout@v3
@@ -31,7 +31,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '3.2'
+          ruby-version: '3.4'
           bundler-cache: true
       - name: Install required gem dependencies
         run: gem install yard redcarpet github-markup --no-document