Update go.mod with deprecated notice (#552)

Author: justinpolygon

go.mod

@@ -2,6 +2,8 @@ module github.com/polygon-io/client-go
 
 go 1.21
 
+// Deprecated: This module has been rebranded and moved to github.com/massive-com/client-go. Please update your imports and dependencies.
+
 require (
 	github.com/cenkalti/backoff/v4 v4.3.0
 	github.com/go-playground/form/v4 v4.2.1