⬆️ ci: upgrade GitHub Actions to latest versions

Fix deprecated actions/upload-artifact v3 causing CI failure.
Upgrade checkout@v4, configure-pages@v5, cache@v4,
upload-pages-artifact@v3, deploy-pages@v4.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lwinmoepaing

.github/workflows/build.yml

@@ -32,19 +32,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Bun
         uses: oven-sh/setup-bun@v1
       - name: Setup Pages
-        uses: actions/configure-pages@v3
+        uses: actions/configure-pages@v5
         with:
           # Automatically inject basePath in your Next.js configuration file and disable
           # server side image optimization (https://nextjs.org/docs/api-reference/next/image#unoptimized).
           #
           # May remove this line if we want to manage the configuration ourself.
           static_site_generator: next
       - name: Restore cache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             .next/cache
@@ -58,7 +58,7 @@ jobs:
       - name: Build with Next.js
         run: bun run build
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: ./out
 
@@ -72,4 +72,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v4