Make TrainingLevelRequirement the correct level of unique

Also updates generateSampleData to match

training/migrations/0005_auto_20210819_1833.py

@@ -0,0 +1,17 @@
+# Generated by Django 3.1.7 on 2021-08-19 17:33
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('training', '0004_auto_20210819_1808'),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name='traininglevelrequirement',
+            unique_together={('level', 'item')},
+        ),
+    ]