title: How do I use C++20 in vscode?
body: <p>I want to use C++20 in vscode as I'd like to use .contains on an unordered_set, but when I try it I get 
  <code>error C2039: 'contains': is not a member of 'std::unordered_set</code>
  and I don't understand why as I 've already went on to c_cpp_properties.json and specified the use of c++20 but it still doesn't seem to work, and I can't find anything anywhere about changing the C++ version on vscode.</p>
  
  <p>Compiler version: <code>19.25.28614 for x86</code></p>