Pass in context to lease done function in client

Allows the client to choose the context to finish the lease.
This allows the client to switch contexts when the main context
used to the create the lease may have been cancelled.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

image.go

@@ -108,7 +108,7 @@ func (i *image) Unpack(ctx context.Context, snapshotterName string) error {
 	if err != nil {
 		return err
 	}
-	defer done()
+	defer done(ctx)
 
 	layers, err := i.getLayers(ctx, platforms.Default())
 	if err != nil {