go.mod: correct major version

fhs · fhs · commit 3c02eec3bcb5 · 2018-02-25T16:15:45.000-05:00
diff --git a/go.mod b/go.mod
@@ -1 +1 @@
-module "github.com/fhs/gompd"
+module "github.com/fhs/gompd/v2"
