Make salvage value a required field on asset

Closes #439

assets/migrations/0024_alter_asset_salvage_value.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2022-02-14 23:43
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0023_alter_asset_purchased_from'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='asset',
+            name='salvage_value',
+            field=models.DecimalField(decimal_places=2, max_digits=10, null=True),
+        ),
+    ]

assets/models.py

@@ -132,7 +132,7 @@ class Asset(models.Model, RevisionMixin):
     date_acquired = models.DateField()
     date_sold = models.DateField(blank=True, null=True)
     purchase_price = models.DecimalField(blank=True, null=True, decimal_places=2, max_digits=10)
-    salvage_value = models.DecimalField(blank=True, null=True, decimal_places=2, max_digits=10)
+    salvage_value = models.DecimalField(null=True, decimal_places=2, max_digits=10)
     comments = models.TextField(blank=True)
 
     # Audit