!14794 fix test case bug

From: @woshixiaoli
Reviewed-by: @zichun_ye,@sunnybeike
Signed-off-by: @zichun_ye

tests/st/probability/distribution/test_categorical_gpu.py

@@ -14,13 +14,13 @@
 # ============================================================================
 """test cases for categorical distribution"""
 
+import pytest
 import numpy as np
 import mindspore.context as context
 import mindspore.nn as nn
 import mindspore.nn.probability.distribution as msd
 from mindspore import Tensor
 from mindspore import dtype as ms
-import pytest
 
 context.set_context(mode=context.GRAPH_MODE, device_target="GPU")
 

tests/st/probability/distribution/test_cauchy_pynative.py

@@ -14,13 +14,13 @@
 # ============================================================================
 """test cases for cauchy distribution"""
 
+import pytest
 import numpy as np
 import mindspore.context as context
 import mindspore.nn as nn
 import mindspore.nn.probability.distribution as msd
 from mindspore import Tensor
 from mindspore import dtype as ms
-import pytest
 
 context.set_context(mode=context.PYNATIVE_MODE, device_target="Ascend")
 

tests/st/probability/distribution/test_gamma_pynative.py

@@ -14,12 +14,12 @@
 # ============================================================================
 """test cases for gamma distribution"""
 
+import pytest
 import numpy as np
 import mindspore.context as context
 import mindspore.nn as nn
 import mindspore.nn.probability.distribution as msd
 from mindspore import dtype as ms
-import pytest
 
 context.set_context(mode=context.PYNATIVE_MODE, device_target="Ascend")