build(nix): adding the flake for nix

flake.nix

@@ -0,0 +1,31 @@
+{
+  description = "Flake utils demo";
+
+  inputs = {
+	nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    c_formatter_42.url = "github:maix0/c_formatter_42-flake";
+  };
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    c_formatter_42,
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in {
+        devShell = pkgs.mkShell {
+          packages = [
+			pkgs.xorg.libX11
+            pkgs.xorg.libXext
+            pkgs.clang
+            pkgs.clang-tools
+            pkgs.norminette
+            c_formatter_42.packages.${system}.default
+            ];
+        };
+      }
+    );
+}