Updated appveyor job to checkout a specific vcpkg commit ID.
Updated appveyor job to checkout a specific vcpkg commit ID.


Former-commit-id: 669412d6360075bdecc7f39870cf88c3e2e6c34d
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin