fix(ci): reactivate Darwin x86_64 build in Hydra CI

Author: jpraynaud

flake.nix

@@ -9,7 +9,7 @@
 
   outputs = inputs:
     inputs.flake-parts.lib.mkFlake {inherit inputs;} {
-      systems = ["x86_64-linux" "aarch64-linux" "aarch64-darwin"];
+      systems = ["x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin"];
 
       imports = [inputs.treefmt-nix.flakeModule];