quickfix multipass launch parameter (#4321)

Author: eddiesimeon

installer/vm_providers/_multipass/_multipass_command.py

@@ -159,7 +159,7 @@ def launch(
         if cpus is not None:
             cmd.extend(["--cpus", cpus])
         if mem is not None:
-            cmd.extend(["--mem", mem])
+            cmd.extend(["--memory", mem])
         if disk is not None:
             cmd.extend(["--disk", disk])
         try: