chore: upgrade actions/download-artifact to v4

.github/workflows/ci.yml

@@ -123,7 +123,7 @@ jobs:
         run: sudo apt-get update && sudo apt-get install -y iproute2
 
       - name: Download Certificates
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: ssl-certs
           path: certs/
@@ -137,7 +137,7 @@ jobs:
         # Disable cache when not using github actions because the runner spends about 3mins trying to upload the cache
         # TODO: setup cache server in Gitea
         if: ${{ github.server_url == 'https://github.com' }}
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.cache/ms-playwright
           key: ${{ runner.os }}-playwright-${{ hashFiles('frontend/bun.lock') }}