Bump mpi-operator dependency

[Jeffwan]

Hi Arena team,

WG-training plans to merge all operators into one. Currently, 1.3.0 has been officially released https://github.com/kubeflow/training-operator/releases/tag/v1.3.0. The only left over is mpi-operator kubeflow/training-operator#1345

We plan to move v1 and v2beta1 mpi to universal training operator soon. At the same time, v1alpha1 will be retired. kubeflow/mpi-operator#422

We take a look at the reference here

arena/pkg/training/trainer_mpi.go

Line 35 in d06b92d

v1alpha1 "github.com/kubeflow/arena/pkg/operators/mpi-operator/apis/kubeflow/v1alpha1"

, seems arena is still using v1alpha1 api, do you have plan to migrate to v1 or even v2beta1?

/cc @wsxiaozhang @cheyang @denkensk
/cc @terrytangyuan @zw0610

[denkensk]

/cc @happy2048