botan3: include static build in passthru.tests

This way its automatically built by ofborg in a PR.

pkgs/development/libraries/botan/default.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchurl,
+  pkgsStatic,
   python3,
   docutils,
   bzip2,
@@ -133,6 +134,10 @@ let
 
       doCheck = true;
 
+      passthru.tests = lib.optionalAttrs (lib.versionAtLeast version "3") {
+        static = pkgsStatic.botan3;
+      };
+
       meta = with lib; {
         description = "Cryptographic algorithms library";
         homepage = "https://botan.randombit.net";