goldberg-emu: fix `gcc-13` build failure

Without the change build fails on `master` as
https://hydra.nixos.org/build/249156752:

In file included from /build/source/dll/base.h:61,
from /build/source/dll/settings.h:18,
from /build/source/dll/settings.cpp:18:
/build/source/dll/settings.h:26:10: error: 'string' in namespace 'std' does not name a type
26 | std::string name;
| ^~~~~~

pkgs/applications/emulators/goldberg-emu/default.nix

···
   # It attempts to install windows-only libraries which we never build
   patches = [ ./dont-install-unsupported.patch ];
 
+  postPatch = ''
+    # Fix gcc-13 build failure due to missing <string> include.
+    sed -e '1i #include <string>' -i dll/settings.h
+  '';
+
   nativeBuildInputs = [ cmake ];
   buildInputs = [ protobuf ];