fix: compilation with clang >=18

[deepak1556]

LLVM >= 18 has deprecated and removed char_trait implementation for non char types in llvm/llvm-project@c366877, for VSCode we build the native modules using libc++ and clang to align with the runtime, building current node-tree-sitter leads to the following error

/mnt/vss/_work/1/s/.build/libcxx_headers/include/__string/char_traits.h:617:23: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'
  617 |   const _CharT* __r = _Traits::find(__p + __pos, __sz - __pos, __c);
      |                       ^
/mnt/vss/_work/1/s/.build/libcxx_headers/include/string:3375:15: note: in instantiation of function template specialization 'std::__str_find<unsigned short, unsigned long, std::char_traits<unsigned short>, 18446744073709551615UL>' requested here
 3375 |   return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
      |               ^
../src/node.cc:484:51: note: in instantiation of member function 'std::basic_string<unsigned short>::find' requested here
  484 |   bool contains(TSSymbol symbol) { return symbols.find(symbol) != symbols.npos; }
      |                                                   ^
/mnt/vss/_work/1/s/.build/libcxx_headers/include/__fwd/string.h:23:29: note: template is declared here
   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;

[amaanq]

thanks!