build(deps): bump actions/download-artifact from 5 to 6 (Lightning-AI#21316)

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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/_build-packages.yml

@@ -51,7 +51,7 @@ jobs:
     needs: build-packages
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with: # download all build artifacts
           pattern: ${{ inputs.artifact-name }}-*
           merge-multiple: true

.github/workflows/ci-pkg-install.yml

@@ -50,7 +50,7 @@ jobs:
       - uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: dist-packages-${{ github.sha }}
           path: dist

.github/workflows/docs-build.yml

@@ -153,7 +153,7 @@ jobs:
       # use input if dispatch or git tag
       VERSION: ${{ inputs.version || github.ref_name }}
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: docs-${{ matrix.pkg-name }}-${{ github.sha }}
           path: docs/build/html/

.github/workflows/release-nightly.yml

@@ -54,7 +54,7 @@ jobs:
       PKG_NAME: "lightning"
     steps:
       - uses: actions/checkout@v5 # needed to use local composite action
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: nightly-packages-${{ github.sha }}
           path: dist

.github/workflows/release-pkg.yml

@@ -38,7 +38,7 @@ jobs:
     if: github.event_name == 'release'
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: dist-packages-${{ github.sha }}
           path: dist
@@ -140,7 +140,7 @@ jobs:
         name: ["FABRIC", "PYTORCH", "LIGHTNING"]
     steps:
       - uses: actions/checkout@v5 # needed for local action below
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: dist-packages-${{ github.sha }}
           path: dist
@@ -165,7 +165,7 @@ jobs:
         name: ["FABRIC", "PYTORCH", "LIGHTNING"]
     steps:
       - uses: actions/checkout@v5 # needed for local action below
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: dist-packages-${{ github.sha }}
           path: dist