Update maven.yml

Author: Allen-Chen-BU

.github/workflows/maven.yml

@@ -36,4 +36,4 @@ jobs:
       uses: actions/upload-artifact@v4
       with:
         name: bu-secondhand-1.0.0
-        path: target/bu-secondhand-1.0.0.jar
+        path: ./code/backend/target/bu-secondhand-1.0.0.jar