[bug] Get rid of wmic in obtaining assigned volume letters for VHD. It's not present on Win11

[mgeeky]

This piece is to be reworked:

https://github.com/mgeeky/PackMyPayload/blob/master/lib/packager.py#L455

            out = Packager.shell('wmic LOGICALDISK LIST BRIEF /format:csv')

Leaving as a note to myself.