add SeResNeXt unittest (#16503)

* add seresnet unittest test=develop

* add dropout layer test=develop

* fix ci test=develop

* fix comment test=develop

* fix comment test=develop

* fix ci test=develop

* fix ci test=develop

* fix ci

* fix module name test=develop

* run imperative serenext unit test serially test=develop

python/paddle/fluid/tests/unittests/CMakeLists.txt

@@ -78,6 +78,7 @@ list(REMOVE_ITEM TEST_OPS test_image_classification_resnet)
 list(REMOVE_ITEM TEST_OPS test_bilinear_interp_op)
 list(REMOVE_ITEM TEST_OPS test_nearest_interp_op)
 list(REMOVE_ITEM TEST_OPS test_imperative_resnet)
+list(REMOVE_ITEM TEST_OPS test_imperative_se_resnext)
 list(REMOVE_ITEM TEST_OPS test_imperative_mnist)
 list(REMOVE_ITEM TEST_OPS test_ir_memory_optimize_transformer)
 foreach(TEST_OP ${TEST_OPS})
@@ -91,6 +92,9 @@ py_test_modules(test_imperative_resnet MODULES test_imperative_resnet ENVS
   FLAGS_cudnn_deterministic=1)
 py_test_modules(test_imperative_mnist MODULES test_imperative_mnist ENVS
   FLAGS_cudnn_deterministic=1)
+py_test_modules(test_imperative_se_resnext MODULES test_imperative_se_resnext ENVS
+  FLAGS_cudnn_deterministic=1 SERIAL)
+
 if(WITH_DISTRIBUTE)
     py_test_modules(test_dist_train MODULES test_dist_train SERIAL)
     set_tests_properties(test_listen_and_serv_op PROPERTIES TIMEOUT 20)