Bump actions/download-artifact from 4 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4...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/dzil-build-and-test.yml

@@ -36,7 +36,7 @@ jobs:
       image: perldocker/perl-tester:5.38
     steps:
       - uses: actions/checkout@v4 # codecov wants to be inside a Git repository
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v6
         with:
           name: build_dir
           path: .
@@ -77,7 +77,7 @@ jobs:
         uses: shogo82148/actions-setup-perl@v1
         with:
           perl-version: ${{ matrix.perl-version }}
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v6
         with:
           name: build_dir
           path: .
@@ -119,7 +119,7 @@ jobs:
         uses: shogo82148/actions-setup-perl@v1
         with:
           perl-version: ${{ matrix.perl-version }}
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v6
         with:
           name: build_dir
           path: .
@@ -155,7 +155,7 @@ jobs:
         with:
           perl-version: ${{ matrix.perl-version }}
           distribution: strawberry # this option only used on windows
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v6
         with:
           name: build_dir
           path: .