Fix GitHub Actions test build

.github/workflows/jekyll.yaml

@@ -11,28 +11,14 @@ jobs:
     timeout-minutes: 10
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.6
-    - name: Cache gems
-      uses: actions/cache@v2
-      with:
-        path: ~/vendor/bundle
-        key: ${{ runner.os }}-gem-${{ hashFiles('**/Gemfile.lock') }}
-        restore-keys: ${{ runner.os }}-gem
+        ruby-version: 3.3
+        bundler-cache: true
     - name: Test site build
       run: |
         ruby --version
-        gem install bundler
-        bundle config path ~/vendor/bundle
-        bundle install --jobs 4 --retry 3
         bundle exec jekyll build
-    - name: Upload site
-      uses: actions/upload-artifact@v2
-      with:
-        name: site
-        path: ./_site/
-        if-no-files-found: ignore