Add integration tests for multiple search engines and enhance error handling

- Implement integration tests for Baidu, Bing, DuckDuckGo, Google, and Yandex.
- Refactor test utility functions to avoid core import cycles.

cmd/root.go

@@ -14,7 +14,7 @@ import (
 )
 
 const (
-	version               = "0.6.2"
+	version               = "0.6.3"
 	defaultConfigFilename = "config"
 	envPrefix             = "OPENSERP"
 )