update image-portait-enhancement trainer

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/10717891

tests/trainers/test_image_portrait_enhancement_trainer.py

@@ -61,6 +61,7 @@ class TestImagePortraitEnhancementTrainer(unittest.TestCase):
             train_dataset=self.dataset_train,
             eval_dataset=self.dataset_val,
             device='gpu',
+            max_epochs=1,
             work_dir=self.tmp_dir)
 
         trainer = build_trainer(
@@ -81,7 +82,7 @@ class TestImagePortraitEnhancementTrainer(unittest.TestCase):
             train_dataset=self.dataset_train,
             eval_dataset=self.dataset_val,
             device='gpu',
-            max_epochs=2,
+            max_epochs=1,
             work_dir=self.tmp_dir)
 
         trainer = build_trainer(