Bump actions/download-artifact from 6 to 7 (#605)

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>
Co-authored-by: Tetsuo Koyama <[email protected]>

Author: dependabot[bot]

.github/workflows/doc.yml

@@ -105,12 +105,12 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           name: doc-build-html
           path: .
 
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           name: doc-build-mini18n-html
           path: .
@@ -168,12 +168,12 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           name: doc-build-html
           path: .
 
-      - uses: actions/download-artifact@v6
+      - uses: actions/download-artifact@v7
         with:
           name: doc-build-mini18n-html
           path: .