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] <[email protected]>

Author: dependabot[bot]

.github/workflows/build.yaml

@@ -172,7 +172,7 @@ jobs:
           - id: "distcheck-debian-stable-amd64-clang"
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-${{ matrix.id }}-source-tree
           path: .

.github/workflows/debian.yml

@@ -80,7 +80,7 @@ jobs:
         with:
           persist-credentials: false
       - name: Download build artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-built-debian-${{ matrix.image_tag }}-${{ matrix.architecture }}
           path: built

.github/workflows/lint.yaml

@@ -74,7 +74,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .
@@ -104,7 +104,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .
@@ -130,7 +130,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .
@@ -167,7 +167,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .
@@ -204,7 +204,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .
@@ -233,7 +233,7 @@ jobs:
     needs: build
     steps:
       - name: Download built source tree archive
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: ola-debian-stable-built-source-tree
           path: .