Bump actions/download-artifact from 6 to 7 (#237)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 6 to 7.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v6...v7)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/nightly.yml

@@ -53,7 +53,7 @@ jobs:
       - uses: actions/checkout@v6
 
       # must be after checkout because it will remove artifacts
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           merge-multiple: true
           path: all-artifacts

.github/workflows/release.yml

@@ -63,7 +63,7 @@ jobs:
       - uses: actions/checkout@v6
 
       # must be after checkout because it will remove artifacts
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           merge-multiple: true
           path: all-artifacts