b/t/toolchain-bundle: add python3.12

Change-Id: Iedf0c35f5f4334bf5c93c5cc937ef855cbabd5c6
Reviewed-on: https://review.monogon.dev/c/monogon/+/4411
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/third_party/nix/default.nix b/third_party/nix/default.nix
index 7688b7f..d868e74 100644
--- a/third_party/nix/default.nix
+++ b/third_party/nix/default.nix
@@ -6,9 +6,10 @@
         (self: super: {
           qemu-minimal = import ./pkgs/qemu { pkgs = super; };
           diffutils = import ./pkgs/diffutils { pkgs = super; };
-          util-linux-minimal = (import ./pkgs/util-linux { pkgs = super; });
+          util-linux-minimal = import ./pkgs/util-linux { pkgs = super; };
           bazel-unwrapped = import ./pkgs/bazel { pkgs = super; };
           perl = import ./pkgs/perl { pkgs = super; };
+          python3Minimal = import ./pkgs/python3 { pkgs = super; };
         })
         (self: super: {
           vde2 = super.vde2.overrideAttrs (oldAttrs: {