Bump actions/download-artifact from 5 to 6 (#199)

Author: dependabot[bot]

.github/workflows/test.yml

@@ -60,7 +60,7 @@ jobs:
         run: python -m pip install --upgrade coverage[toml]
 
       - name: Download data
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           pattern: coverage-data-*
           merge-multiple: true