added missing migration for snapshot id

Author: yvess

django/gsmap/migrations/0018_auto_20200510_1742.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.3 on 2020-05-10 17:42
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('gsmap', '0017_auto_20200429_2118'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='snapshot',
+            name='id',
+            field=models.CharField(max_length=8, primary_key=True, serialize=False, unique=True),
+        ),
+    ]