Added CodeQL flake

codeql/samples/flake.nix

@@ -0,0 +1,24 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+        lib = pkgs.lib;
+
+        shellWithPkgs = buildInputs: pkgs.mkShell {
+          inherit buildInputs;
+        };
+      in
+      {
+        devShells.default = shellWithPkgs (lib.singleton pkgs.codeql);
+      });
+}
+