Mark migrations with data operations "non atomic"

Ref: https://docs.djangoproject.com/en/dev/howto/writing-migrations/#non-atomic-migrations

InvenTree/company/migrations/0019_auto_20200413_0642.py

@@ -354,6 +354,8 @@ def associate_manufacturers(apps, schema_editor):
 
 class Migration(migrations.Migration):
 
+    atomic = False
+
     dependencies = [
         ('company', '0018_supplierpart_manufacturer'),
     ]

InvenTree/company/migrations/0024_unique_name_email_constraint.py

@@ -19,6 +19,8 @@ def make_empty_email_field_null(apps, schema_editor):
 
 class Migration(migrations.Migration):
 
+    atomic = False
+
     dependencies = [
         ('company', '0023_auto_20200808_0715'),
     ]

InvenTree/company/migrations/0026_auto_20201110_1011.py

@@ -138,6 +138,8 @@ def reverse_currencies(apps, schema_editor):
 
 class Migration(migrations.Migration):
 
+    atomic = False
+
     dependencies = [
         ('company', '0025_auto_20201110_1001'),
     ]