Bump dawidd6/action-download-artifact from 2 to 6

Bumps [dawidd6/action-download-artifact](https://github.com/dawidd6/action-download-artifact) from 2 to 6.
- [Release notes](https://github.com/dawidd6/action-download-artifact/releases)
- [Commits](dawidd6/action-download-artifact@v2...v6)

---
updated-dependencies:
- dependency-name: dawidd6/action-download-artifact
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/flatpak-repo.yml

@@ -64,7 +64,7 @@ jobs:
           sudo apt-get install -y flatpak flatpak-builder ostree
 
       - name: Download Flatpak Bundle
-        uses: dawidd6/action-download-artifact@v2
+        uses: dawidd6/action-download-artifact@v6
         with:
           name: flatpak-bundle
           path: .
@@ -206,7 +206,7 @@ jobs:
           fi
 
       - name: Download appdata.xml
-        uses: dawidd6/action-download-artifact@v2
+        uses: dawidd6/action-download-artifact@v6
         with:
           name: appdata-xml
           workflow: ${{ github.event.workflow_run.workflow_id }}