A landlord who wants a unit vacant for a sale still has to work within those same rules; there is no separate faster notice period in Saskatchewan just because the property is listed. The notice must be in writing and state the date the tenancy is expected to end.
A buyer who plans to occupy the home themselves can, in some circumstances, use the Residential Tenancies Act, 2006's process for ending a tenancy for the landlord's own use, but that is a specific ground with its own notice period, not something a seller can simply impose to speed up a sale.
Selling with a tenant still in place is often faster and just as profitable as forcing a vacancy first. Get your hand-reviewed valuation from Joel Dyck.