Bump actions/upload-artifact from 5 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

See gh-48537

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/build-pull-request.yml

@@ -18,7 +18,7 @@ jobs:
         uses: ./.github/actions/print-jvm-thread-dumps
       - name: Upload Build Reports
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: build-reports
           path: '**/build/reports/'

.github/workflows/verify.yml

@@ -79,7 +79,7 @@ jobs:
         run: ./gradlew spring-boot-release-verification-tests:test
       - name: Upload Build Reports on Failure
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: build-reports
           path: '**/build/reports/'