fix(nix): Use rustup instead of indivual components

This lets us correctly use the toolchain from rust-toolchain.toml, instead of hard setting to rustc (and co).

Author: NickLarsenNZ

shell.nix

@@ -6,8 +6,7 @@
 
 pkgs.mkShell {
   packages = with pkgs; [
-    cargo
-    rustc
+    rustup
     nodejs
     zizmor
   ];