Update GitHub Actions workflows to use version 4 of upload and download artifact actions

Author: pixelead0

.github/workflows/build.yml

@@ -55,7 +55,7 @@ jobs:
       # Solo para main: guardar el sitio construido
       - name: Upload build artifact
         if: github.ref == 'refs/heads/main'
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: site
           path: site/

.github/workflows/deploy.yml

@@ -26,7 +26,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - name: Download build artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: site
           path: site/
@@ -37,7 +37,7 @@ jobs:
         uses: actions/configure-pages@v4
 
       - name: Upload to GitHub Pages
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
         with:
           path: site/