Update vcpkg to 2024.06.15

[duncanpo]

Currently at 2024.02.14, which is 7 releases behind. Latest release is 2024.08.23
https://github.com/microsoft/vcpkg/releases

[duncanpo]

Original plan to update to 2024.08.23. However, that version has an issue on Mac that the install name of curl is not properly set. It is possible to use install_name_tool to correct the problem. But for now we can update to 2024.06.15 instead, and wait and see the next time when we update, whether the problem has been fixed.