docs: Update README.md (#196)

Author: dogun-anduril

README.md

@@ -20,7 +20,7 @@ To use the SDK please ensure you have the following installed:
 Install the Lattice SDK package with
 
 ```
-go get github.com/anduril/lattice-sdk-go/v2
+go get github.com/anduril/lattice-sdk-go/v3
 ```
 
 ## Support