fix(third_party/nixpkgs/crate2nix): reintroduce tests in debug patch

This is was dropped accidentially, but we actually want to run tests in
debug mode, to check for overflows.

Change-Id: Ic0cf2d4a263bfd71f3453ed335d8be9dacd945e8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10932
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/Cargo.nix

@@ -13342,6 +13342,7 @@ rec {
               (
                 _: {
                   buildTests = true;
+                  release = false;
                 }
               );
             # If the user hasn't set any pre/post commands, we don't want to