fixed extra-conversion

handlers/BasicPrmonMetrics.py

@@ -54,7 +54,7 @@ class BasicPrmonMetrics(BaseHandler):
                     for i, h in enumerate(headers):
                         data[h].append(vals[i])
 
-            return json.dumps(data)
+            return data
 
         except FileNotFoundError:
             log.error(f"failed to locate {file_path}")