Update supported go versions to 1.20 and 1.21
diff --git a/go.mod b/go.mod
index 5f2a2c8..7be4256 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module github.com/apache/thrift
 
-go 1.19
+go 1.20