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](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]>

Author: dependabot[bot]

.github/workflows/gradle.yml

@@ -104,7 +104,7 @@ jobs:
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v5
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: app-main
           path: build/libs/

.github/workflows/release.yml

@@ -66,7 +66,7 @@ jobs:
         run: ./gradlew publish -Pcom.enonic.xp.app.production=true -PrepoKey=${{ steps.publish_vars.outputs.repo }} -PrepoUser=ci -PrepoPassword=${{ secrets.ARTIFACTORY_PASSWORD }}
 
       - name: Download changelog
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: changelog