scion: add passthru.tests

pkgs/by-name/sc/scion/package.nix

@@ -2,6 +2,7 @@
 , buildGoModule
 , fetchFromGitHub
 , fetchpatch2
+, nixosTests
 }:
 let
   version = "0.10.0";
@@ -61,6 +62,10 @@ buildGoModule {
     })
   ];
 
+  passthru.tests = {
+    inherit (nixosTests) scion-freestanding-deployment;
+  };
+
   meta = with lib; {
     description = "A future Internet architecture utilizing path-aware networking";
     homepage = "https://scion-architecture.net/";