Update actions/download-artifact action to v8

Author: renovate[bot]

.github/workflows/appimage.yml

@@ -42,7 +42,7 @@ jobs:
     permissions: write-all
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/download-artifact@018cc2cf5baa6db3ef3c5f8a56943fffe632ef53 # v6.0.0
+      - uses: actions/download-artifact@70fc10c6e5e1ce46ad2ea6f2b72d43f7d47b13c3 # v8.0.0
         with:
           pattern: AppImage-*
           merge-multiple: true