wesnoth: backport gcc-13 fix

Without the change `wesnoth` fails to build against `gcc-13` as:

$ nix build --impure --expr 'with import <nixpkgs> {}; wesnoth.override { stdenv = gcc13Stdenv; }' -L

In file included from /build/source/src/serialization/base64.cpp:16:
/build/source/src/serialization/base64.hpp:23:49: error: 'uint8_t' was not declared in this scope
23 | using byte_string_view = std::basic_string_view<uint8_t>;
| ^~~~~~~
/build/source/src/serialization/base64.hpp:20:1: note: 'uint8_t' is defined in header '<cstdint>'; did you forget to '#include <cstdint>'?
19 | #include <vector>
+++ |+#include <cstdint>
20 |

pkgs/games/wesnoth/default.nix

···
-{ lib, stdenv, fetchFromGitHub, cmake, pkg-config, SDL2, SDL2_image, SDL2_mixer, SDL2_net, SDL2_ttf
+{ lib, stdenv, fetchFromGitHub, fetchpatch
+, cmake, pkg-config, SDL2, SDL2_image, SDL2_mixer, SDL2_net, SDL2_ttf
 , pango, gettext, boost, libvorbis, fribidi, dbus, libpng, pcre, openssl, icu
 , Cocoa, Foundation
 }:
···
     repo = "wesnoth";
     hash = "sha256-KtAPc2nsqSoHNsLTLom/yaUECn+IWBdBFpiMclrUHxM=";
   };
+
+  patches = [
+    # Pull upstream fix https://github.com/wesnoth/wesnoth/pull/6726
+    # for gcc-13 support.
+    (fetchpatch {
+      name = "gcc-134.patch";
+      url = "https://github.com/wesnoth/wesnoth/commit/f073493ebc279cefa391d364c48265058795e1d2.patch";
+      hash = "sha256-uTB65DEBZwHFRgDwNx/yVjzmnW3jRoiibadXhNcwMkI=";
+    })
+  ];
 
   nativeBuildInputs = [ cmake pkg-config ];