Add new model "NotificationEntry"

- Keep track of past notifications

InvenTree/common/migrations/0012_notificationentry.py

@@ -0,0 +1,25 @@
+# Generated by Django 3.2.5 on 2021-11-03 13:54
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('common', '0011_auto_20210722_2114'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='NotificationEntry',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('key', models.CharField(max_length=250)),
+                ('uid', models.IntegerField()),
+                ('updated', models.DateTimeField(auto_now=True)),
+            ],
+            options={
+                'unique_together': {('key', 'uid')},
+            },
+        ),
+    ]