Bump actions/download-artifact from 5 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/build-debian-multiarch.yml

@@ -121,7 +121,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
     - name: Download all multiarch artifacts
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v6
       with:
         name: pygame-multiarch-armv7-dist
         path: ~/artifacts

.github/workflows/release-gh-draft.yml

@@ -29,7 +29,7 @@ jobs:
       - uses: actions/checkout@v5.0.0
 
       - name: Download all artifacts
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           path: pygame-wheels
           merge-multiple: true