[BUG] Ref count of numpy array inside list is wrong when compiling with the latest standard on Microsoft Visual Studio

Issue description

Ref count of numpy array is wrong and causes a leak when compiled in Visual Studio with the standard set to latest. It is fine when set so C++ 17.

Development environment : Windows 10
Visual Studio Version 16.9.5
Intel® C++ Compiler Package ID: w_comp_lib_2020.1.216
Python version is 3.8.6
numpy version is 1.21

Reproducible example code

//binding.cpp
#include <pybind11/pybind11.h>
#include <pybind11/numpy.h>
#include <pybind11/stl.h>

namespace py = pybind11;

void function_that_does_nothing(std::vector<py::array_t<float>>& images)
{
    return;
}

PYBIND11_MODULE(Project1, m) {
    m.def("function_that_does_nothing", &function_that_does_nothing);
}

//main.py
import sys
import Project1 as project
import numpy as np


something_to_process = []
arr = np.ones((3008, 4112))
something_to_process.append(arr)
project.function_that_does_nothing(something_to_process)
print(f"The ref count ----> {sys.getrefcount(something_to_process[0])}")

The Visual Studio option of interest is under Project -> Properties -> General ->C++ Language Standard. To see the issue, you can try compiling with the option set to Preview - Features from the Latest C++ Working Draft (/std:c++latest) then set to ISO C++17 Standard (/std:c++17).

Thank you

Start with the binding.cpp and main.py reproducer, compiling it in Visual Studio with /std:c++latest and /std:c++17. Compare the reported reference count and leak behavior for the numpy array passed inside the list. Done means the latest standard no longer produces an incorrect reference count or leak while the C++17 behavior remains correct.