Update GitHub Artifact Actions (#52)

Author: renovate[bot]

.github/workflows/publish.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Build Web
         run: flutter build web --release
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: build
           path: build
@@ -40,7 +40,7 @@ jobs:
       - uses: actions/checkout@v5
         name: Checkout
       - name: Download build artifacts
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: build
           path: build