chore(deps): update actions/upload-artifact action to v6

Author: renovate[bot]

.github/workflows/maven.yml

@@ -29,15 +29,15 @@ jobs:
         run: mvn -B package --file pom.xml -Dgpg.skip
 
       - name: "Upload artifacts"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: artifacts
           path: "**/target/"
           retention-days: 5
           include-hidden-files: true
 
       - name: "Upload assets"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: assets
           path: ".asset/"