fix: GitHub Actions のアクションバージョンを更新

- actions/upload-pages-artifact@v2 → v3
- actions/deploy-pages@v2 → v4
- 非推奨バージョンのエラーを修正

.github/workflows/pages.yml

@@ -53,7 +53,7 @@ jobs:
           JEKYLL_ENV: production
           
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: docs/_site
 
@@ -68,7 +68,7 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v4
         
       - name: Notify deployment success
         run: |