[API Enhancement] No.6 support single `int` input in UpsamplingNearest2D and...

[API Enhancement] No.6 support single `int` input in UpsamplingNearest2D and UpsamplingBilinear2D (#56470)

* enhance single int input in UpsamplingNearest2D and UpsamplingBilinear2D

* add unittest

* add unittest

python/paddle/nn/layer/common.py

@@ -489,6 +489,8 @@ class UpsamplingNearest2D(Layer):
         self, size=None, scale_factor=None, data_format='NCHW', name=None
     ):
         super().__init__()
+        if isinstance(size, int):
+            size = [size, size]
         self.size = size
         self.scale_factor = scale_factor
         self.data_format = data_format
@@ -575,6 +577,8 @@ class UpsamplingBilinear2D(Layer):
         self, size=None, scale_factor=None, data_format='NCHW', name=None
     ):
         super().__init__()
+        if isinstance(size, int):
+            size = [size, size]
         self.size = size
         self.scale_factor = scale_factor
         self.data_format = data_format

test/legacy_test/test_imperative_layers.py

@@ -116,11 +116,21 @@ class TestLayerPrint(unittest.TestCase):
             str(module), 'UpsamplingNearest2D(size=[12, 12], data_format=NCHW)'
         )
 
+        module = nn.UpsamplingNearest2D(size=12)
+        self.assertEqual(
+            str(module), 'UpsamplingNearest2D(size=[12, 12], data_format=NCHW)'
+        )
+
         module = nn.UpsamplingBilinear2D(size=[12, 12])
         self.assertEqual(
             str(module), 'UpsamplingBilinear2D(size=[12, 12], data_format=NCHW)'
         )
 
+        module = nn.UpsamplingBilinear2D(size=12)
+        self.assertEqual(
+            str(module), 'UpsamplingBilinear2D(size=[12, 12], data_format=NCHW)'
+        )
+
         module = nn.Bilinear(in1_features=5, in2_features=4, out_features=1000)
         self.assertEqual(
             str(module),