Made mapping testing page nullable

plugins/netbox-rps-plugin/netbox_rps_plugin/migrations/0004_testingpage_nullable.py

+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('netbox_rps_plugin', '0003_http_header_unique_constraint')
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='mapping',
+            name='testingpage',
+            field=models.CharField(max_length=120, null=True, blank=True),
+        ),
+    ]