Wrong API call name

[cyber4len]

https://github.com/plesk/SolusVM-WHMCS-Module/blob/c1f109e090d315cec8a544867e765ae71e88678e/modules/servers/solusvmpro/solusvmpro.php#L1038

Call should be set as "vserver-vncpass" instead of "vserver-vncpassword": https://docs.solusvm.com/display/DOCS/Change+VNC+Password