Update supported go version to 1.18.* and 1.19.*

Client: go

Also provide generic version of Pointer helper function.
diff --git a/go.mod b/go.mod
index d620e5e..2d3d1c6 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,5 @@
 module github.com/apache/thrift
 
-go 1.16
+go 1.18
 
 require github.com/golang/mock v1.5.0