[db] Make sender an EmailField

this will accomodate the larger size

tcms_github_marketplace/migrations/0003_sender_email_field.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.1 on 2019-05-25 18:43
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('tcms_github_marketplace', '0002_update_fields'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='purchase',
+            name='sender',
+            field=models.EmailField(db_index=True, max_length=254),
+        ),
+    ]

tcms_github_marketplace/models.py

@@ -14,7 +14,7 @@ class Purchase(models.Model):
     """
     vendor = models.CharField(max_length=16, db_index=True, blank=True, null=True)
     action = models.CharField(max_length=64, db_index=True)
-    sender = models.CharField(max_length=64, db_index=True)
+    sender = models.EmailField(db_index=True)
     effective_date = models.DateTimeField(db_index=True)
 
     # this is for internal purposes