Fix: rank feature score should be greater than 0. (#8416)

### What problem does this PR solve?

#8414

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/prompts.py

@@ -427,6 +427,7 @@ Output:
     res = {}
     for k, v in obj.items():
         try:
+            if int(v) > 0:
                 res[str(k)] = int(v)
         except Exception:
             pass