修复若干bug，优化若干代码

apps/work/migrations/0001_initial.py

@@ -1,4 +1,4 @@
-# Generated by Django 3.2.5 on 2022-05-07 01:48
+# Generated by Django 3.2.5 on 2022-05-11 14:01
 
 from django.db import migrations, models
 

apps/work/migrations/0002_alter_works_img.py

@@ -1,6 +1,7 @@
-# Generated by Django 3.2.5 on 2022-05-05 21:57
+# Generated by Django 3.2.5 on 2022-05-15 00:27
 
 from django.db import migrations, models
+import utils.ImageStorage
 
 
 class Migration(migrations.Migration):
@@ -13,6 +14,6 @@ class Migration(migrations.Migration):
         migrations.AlterField(
             model_name='works',
             name='img',
-            field=models.ImageField(blank=True, null=True, upload_to='image', verbose_name='图片'),
+            field=models.ImageField(blank=True, null=True, storage=utils.ImageStorage.ImageStorage(), upload_to='image', verbose_name='图片'),
         ),
     ]