feat: fix v2 issue

Author: yihau

README.md

@@ -25,7 +25,7 @@ Also feel free to post a issue for missing content.
 ### Installing
 
 ```sh
-go get -v github.com/portto/solana-go-sdk@v2.0.0
+go get -v github.com/portto/solana-go-sdk@v1.9.0
 ```
 
 ### Example