Update actions/download-artifact action to v5

Author: renovate[bot]

.github/workflows/verify.yml

@@ -146,7 +146,7 @@ jobs:
           . venv/bin/activate
           uv pip install -r requirements.txt -r requirements-test.txt
       - name: Download all coverage artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v5
       - name: Combine coverage results
         run: |
           . venv/bin/activate