Update workflow environment

.github/workflows/build.yml

@@ -8,17 +8,17 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     strategy:
       matrix:
-        node-version: [12.x]
+        node-version: [20.x]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
 
@@ -28,7 +28,7 @@ jobs:
           npm run build
 
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v3
+        uses: peaceiris/actions-gh-pages@v4
         with:
           publish_dir: ./_site
           github_token: ${{ secrets.GITHUB_TOKEN }}