Use quantity instead of usage_count

uncloud_pay/migrations/0003_auto_20200621_1442.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.6 on 2020-06-21 14:42
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('uncloud_pay', '0002_auto_20200621_1335'),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name='billrecord',
+            old_name='usage_count',
+            new_name='quantity',
+        ),
+    ]