Bug in bdschur with sorting

There is a bug in the block-diagonal schur matrix computation in [line 473](https://github.com/python-control/python-control/blob/56b9402a2f295e6c632cd35510a40461538ce5a9/control/canonical.py#L473). It should be `tmodal = tmodal @ rperm.T`. Otherwise `tmodal @ amodal @ np.linalg.inv(tmodal)` $\neq$ `a` where `a` is the input to the function.