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](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>

.github/workflows/daily-backlog-burner.lock.yml

@@ -2946,7 +2946,7 @@ jobs:
     steps:
       - name: Download patch artifact
         continue-on-error: true
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: aw.patch
           path: /tmp/

.github/workflows/daily-perf-improver.lock.yml

@@ -3021,7 +3021,7 @@ jobs:
     steps:
       - name: Download patch artifact
         continue-on-error: true
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: aw.patch
           path: /tmp/

.github/workflows/daily-test-improver.lock.yml

@@ -2996,7 +2996,7 @@ jobs:
     steps:
       - name: Download patch artifact
         continue-on-error: true
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: aw.patch
           path: /tmp/

.github/workflows/pr-fix.lock.yml

@@ -3371,7 +3371,7 @@ jobs:
     steps:
       - name: Download patch artifact
         continue-on-error: true
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: aw.patch
           path: /tmp/