Update supported go versions

Following our policy regarding supported go releases, change the
supported go versions to 1.19.* and 1.20.* with the release of go 1.20.
diff --git a/lib/go/test/go.mod b/lib/go/test/go.mod
index 37814e0..1c6d80d 100644
--- a/lib/go/test/go.mod
+++ b/lib/go/test/go.mod
@@ -1,6 +1,6 @@
 module github.com/apache/thrift/lib/go/test
 
-go 1.18
+go 1.19
 
 require (
 	github.com/apache/thrift v0.0.0-00010101000000-000000000000