Fix the pebble's db path

pkg/core/db.go

@@ -23,7 +23,7 @@ type DB struct {
 }
 
 func CreateDB(path *string) (*DB, error){
-	conn, err := pebble.Open("demo", &pebble.Options{})
+	conn, err := pebble.Open(*path, &pebble.Options{})
 	if err != nil {
 		return nil, err
 	}