avec les migrations c'est mieux

users/migrations/0002_auto_20180827_1409.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.1 on 2018-08-27 12:09
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('users', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='user',
+            name='last_name',
+            field=models.CharField(blank=True, max_length=150, verbose_name='last name'),
+        ),
+    ]