ci: upgrade to download-action v8

.github/actions/test-summary/action.yml

@@ -16,7 +16,7 @@ runs:
   using: "composite"
   steps:
     - name: Download test result rows
-      uses: actions/download-artifact@v4
+      uses: actions/download-artifact@v8
       with:
         pattern: ${{ inputs.download-pattern }}
         merge-multiple: true

.github/workflows/ci-comment.yml

@@ -25,7 +25,7 @@ jobs:
       # Allow failure so the "Delete PR comment" step still runs to clean up stale comments.
       - name: Download summaries
         id: download
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v8
         continue-on-error: true
         with:
           run-id: ${{ github.event.workflow_run.id }}

.github/workflows/continuous-integration.yml

@@ -434,7 +434,7 @@ jobs:
         uses: ./.github/actions/get-version
 
       - name: Download artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v8
 
       - name: Generate package checksums
         id: generate_notes