Resolve "Negative values for tardiness are not rejected"

Closes #141 (closed)

aleksis/apps/alsijil/migrations/0011_tardiness_positive.py

+# Generated by Django 3.1.6 on 2021-02-26 17:45
+
+from django.db import migrations, models
+
+
+def fix_negative_tardiness(apps, schema_editor):
+    PersonalNote = apps.get_model("alsijil", "PersonalNote")
+    PersonalNote.objects.filter(late__lt=0).update(late=0)
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('alsijil', '0010_events_extra_lessons'),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_negative_tardiness),
+        migrations.AlterField(
+            model_name='personalnote',
+            name='late',
+            field=models.PositiveSmallIntegerField(default=0),
+        ),
+    ]