chore(ci)(deps): bump actions/download-artifact from 7 to 8 (#7187)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 7 to 8.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v7...v8)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -477,7 +477,7 @@ jobs:
       - name: Download test shard attestations
         id: attestations
         continue-on-error: true
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           pattern: shard-attest-test-*
           path: ${{ runner.temp }}/shard-attestations
@@ -1020,7 +1020,7 @@ jobs:
       - name: Download dogfood attestations
         id: attestations
         continue-on-error: true
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           pattern: shard-attest-dogfood-*
           path: ${{ runner.temp }}/shard-attestations