add AvgPooling layer

mindspore/nn/layer/pooling.py

@@ -258,7 +258,7 @@ class AvgPool1d(_PoolNd):
         [[[[8. 8. 7. 4.]
            [8. 4. 0. 9.]
            [6. 4. 6. 1.]
-           [6. 8. 8. 5.]
+           [6. 8. 8. 5.]]
           [[4. 8. 5. 4.]
            [8. 4. 7. 5.]
            [3. 5. 3. 9.]
@@ -270,7 +270,7 @@ class AvgPool1d(_PoolNd):
         [[[[7.6640625 6.3320312]
            [4.        4.3320312]
            [5.3320312 3.6660156]
-           [7.3320312 7        ]
+           [7.3320312 7        ]]
           [[5.6640625 5.6640625]
            [6.3320312 5.3320312]
            [3.6660156 5.6640625]