Bump actions/download-artifact from 7 to 8 (#61)

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
...

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -83,7 +83,7 @@ jobs:
     needs: build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@v8
       - run: sh -exc 'for d in *; do cd $d; tar --extract --file artifact.tar --verbose; cd ..; done'
       - run: cp github-release-${{ github.sha }}-ghc-9.12-ubuntu-24.04/artifact/${{ env.PREFIX }}.tar.gz .
       - run: tar --auto-compress --create --file ../../${{ env.PREFIX }}-darwin-arm64.tar.gz --verbose github-release