build(deps): bump actions/download-artifact from 5 to 6 (#2235)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yaml

@@ -37,7 +37,7 @@ jobs:
         run: make check test
       - name: Archive built binaries
         run: tar -cvf built-binaries.tar helmfile diff-yamls dyff
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v5
         with:
           name: built-binaries-${{ github.run_id }}
           path: built-binaries.tar
@@ -92,7 +92,7 @@ jobs:
         with:
           go-version-file: go.mod
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: built-binaries-${{ github.run_id }}
       - name: install semver
@@ -127,7 +127,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: built-binaries-${{ github.run_id }}
       - name: Extract tar to get built binaries