Add optional openssl dep on linux

flake.nix

@@ -16,6 +16,11 @@
 
         root = ./.;
         cargoBuildOptions = opts: opts ++ [ "--package youmubot" ];
+
+        nativeBuildInputs = nixpkgs.lib.optionals (nixpkgs.lib.strings.hasSuffix "linux" system) (with pkgs; [
+          pkg-config
+          openssl
+        ]);
       };
 
       defaultPackage = packages.youmubot;