Show the status for the correct schema (#204)

Fix the `pgroll status` command so that it shows the status for the
correct schema (ie the one set by the `--schema` flag, or `"public"` by
default).

Prior to this the command would show the status for the
`--pgroll-schema` (`"pgroll"` by default).

This appears to have been broken since #152.

cmd/status.go

@@ -30,7 +30,7 @@ var statusCmd = &cobra.Command{
 		}
 		defer state.Close()
 
-		statusLine, err := statusForSchema(ctx, state, flags.StateSchema())
+		statusLine, err := statusForSchema(ctx, state, flags.Schema())
 		if err != nil {
 			return err
 		}