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] <[email protected]>

Author: dependabot[bot]

.github/workflows/build.yaml

@@ -115,7 +115,7 @@ jobs:
         with:
           python-version: "3.x"
       # download everything
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           path: artifacts/
       # collate and report

.github/workflows/publish_to_pypi.yaml

@@ -35,7 +35,7 @@ jobs:
       id-token: write
 
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: packages
           path: dist
@@ -48,7 +48,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: packages
           path: dist

.github/workflows/publish_to_test_pypi.yaml

@@ -51,7 +51,7 @@ jobs:
       id-token: write
 
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: packages
           path: dist