REG_NOTIFY_THREAD_AGNOSTIC should be attributed as requiring 

Per [the docs](https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regnotifychangekeyvalue#parameters), the `REG_NOTIFY_FILTER.REG_NOTIFY_THREAD_AGNOSTIC` flag is only available on Windows 8 and later. The metadata has an attribute for members that are only available on particular Windows versions, but it doesn't appear on this enum value.