build(deps): bump actions/download-artifact from 6 to 7

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]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -447,13 +447,13 @@ jobs:
         with:
           path: iguana_src
       - name: download documentation artifacts
-        uses: actions/download-artifact@v6
+        uses: actions/download-artifact@v7
         with:
           pattern: doc_web*
           path: pages
           merge-multiple: true
       - name: download coverage report
-        uses: actions/download-artifact@v6
+        uses: actions/download-artifact@v7
         with:
           name: coverage-report
           path: coverage-report