Update supported go versions to 1.20 and 1.21
diff --git a/test/go/go.mod b/test/go/go.mod
index ff88c9b..723069b 100644
--- a/test/go/go.mod
+++ b/test/go/go.mod
@@ -1,6 +1,6 @@
 module github.com/apache/thrift/test/go
 
-go 1.19
+go 1.20
 
 require (
 	github.com/apache/thrift v0.0.0-00010101000000-000000000000