refine redis connection (#599)

### What problem does this PR solve?

#591 

### Type of change

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

rag/app/table.py

                 cell.value for i,
                 cell in enumerate(
                     rows[0]) if i not in missed]
+            if not headers:continue
             data = []
             for i, r in enumerate(rows[1:]):
                 rn += 1

rag/utils/redis_conn.py

 
     def __open__(self):
         try:
-            self.REDIS = redis.Redis(host=self.config.get("host", "redis").split(":")[0],
+            self.REDIS = redis.StrictRedis(host=self.config["host"].split(":")[0],
                                      port=int(self.config.get("host", ":6379").split(":")[1]),
                                      db=int(self.config.get("db", 1)),
-                                     password=self.config.get("password"))
+                                     password=self.config["password"])
         except Exception as e:
             logging.warning("Redis can't be connected.")
         return self.REDIS