Bump actions/download-artifact from 5 to 6 (#519)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
           # Sonar analysis needs the full history for features like automatic assignment of bugs. If the following step
           # is not included the project will show a warning about incomplete information.
           fetch-depth: 0
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: code-coverage-ubuntu-latest-22.x
           path: coverage/