Bump actions/download-artifact from 3 to 4 (#95)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v3...v4)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  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: Andy Coates <[email protected]>

.github/workflows/gh-pages.yml

@@ -147,22 +147,22 @@ jobs:
         id: pages
         uses: actions/configure-pages@f156874f8191504dae5b037505266ed5dda6c382 # v3.0.6
       - name: Download implementations
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: implementations
           path: docs/_includes
       - name: Download functional results
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: functional
           path: docs/_includes
       - name: Download validate benchmark results
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: validateBenchmark
           path: docs/_includes
       - name: Download serde benchmark results
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: serdeBenchmark
           path: docs/_includes