fix(third_party/crate2nix): run tests in debug mode

Behave like `cargo test` rather than `cargo test --release`.

Change-Id: Ie013d04ac68d7dec2a3b870fa9f0060a70a9635d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9621
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

third_party/overlays/patches/crate2nix-tests-debug.patch

@@ -0,0 +1,12 @@
+diff --git a/templates/nix/crate2nix/default.nix b/templates/nix/crate2nix/default.nix
+index 4eefda8..d064118 100644
+--- a/templates/nix/crate2nix/default.nix
++++ b/templates/nix/crate2nix/default.nix
+@@ -111,6 +111,7 @@ rec {
+             (
+               _: {
+                 buildTests = true;
++                release = false;
+               }
+             );
+           # If the user hasn't set any pre/post commands, we don't want to