noexcept specifiers on valur_or() and error_or() not work in C++17

[X1aomu]

expected/include/zeus/expected.hpp

Lines 1684 to 1686 in 6031d40

	#if __cplusplus >= 202'002L // doesn't compile with C++17 with MSVC, may be a compiler bug
	noexcept(std::is_nothrow_copy_constructible_v<T> && std::is_nothrow_convertible_v<U, T>)
	#endif

Such thing was a bug because is_nothrow_convertible is not available in C++17, thus not any compiler bugs was there.