Bump actions/download-artifact from 3 to 4

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]>

.github/workflows/main.yml

@@ -222,17 +222,17 @@ jobs:
       - name: Clone Git repository
         uses: actions/checkout@v3
       - name: Retrieve Linux external
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: Linux Pd external
           path: asdf
       - name: Retrieve macOS external
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: macOS Pd external
           path: asdf
       - name: Retrieve Windows external
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: Windows Pd external
           path: asdf