Update db.py

Fix for bhagavat gita count

db.py

@@ -630,7 +630,7 @@ class SanatanDatabase:
         cached_entry = self._count_cache.get(collection_name)
         if cached_entry:
             ts, cached_count = cached_entry
-            if now - ts < self._cache_ttl:
+            if now - ts < self._cache_ttl and cached_count > 0:
                 logger.debug("Cache hit for collection [%s]: %d", collection_name, cached_count)
                 return cached_count
             else: