remove JobTemplate.job_type = 'scan'

see: https://github.com/ansible/awx/issues/5603

awx/main/migrations/0104_v370_cleanup_old_scan_jts.py

@@ -0,0 +1,24 @@
+# Generated by Django 2.2.8 on 2020-01-15 20:01
+
+from django.db import migrations, models
+
+
+def cleanup_scan_jts(apps, schema_editor):
+    JobTemplate = apps.get_model('main', 'JobTemplate')
+    JobTemplate.objects.filter(job_type='scan').update(job_type='run')
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0103_v370_remove_computed_fields'),
+    ]
+
+    operations = [
+        migrations.RunPython(cleanup_scan_jts),
+        migrations.AlterField(
+            model_name='jobtemplate',
+            name='job_type',
+            field=models.CharField(choices=[('run', 'Run'), ('check', 'Check')], default='run', max_length=64),
+        ),
+    ]