fix circular deps of sbp python module

[jackalcooper]

No description provided.

[github-actions]

Speed stats:

GPU Name: GeForce GTX 1080 

PyTorch resnet50 time: 140.4ms (= 7020.1ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 126.7ms (= 6334.3ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
Relative speed: 1.11 (= 140.4ms / 126.7ms)

PyTorch resnet50 time: 83.2ms (= 4159.4ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 74.0ms (= 3700.9ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
Relative speed: 1.12 (= 83.2ms / 74.0ms)

PyTorch resnet50 time: 60.5ms (= 3024.2ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 47.6ms (= 2379.9ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
Relative speed: 1.27 (= 60.5ms / 47.6ms)

PyTorch resnet50 time: 46.1ms (= 2305.7ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 45.0ms (= 2249.2ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
Relative speed: 1.03 (= 46.1ms / 45.0ms)

PyTorch resnet50 time: 42.5ms (= 2125.1ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 43.3ms (= 2165.8ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
Relative speed: 0.98 (= 42.5ms / 43.3ms)