#229 Shared users mandatory on admin

* changes mandatory state of users and teams on admin backend to optional (as expected by the model)
* adds team selection to admin backend

intervention/migrations/0008_auto_20221116_1322.py

@@ -0,0 +1,26 @@
+# Generated by Django 3.1.3 on 2022-11-16 12:22
+
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('user', '0006_auto_20220815_0759'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('intervention', '0007_auto_20220815_1030'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='intervention',
+            name='teams',
+            field=models.ManyToManyField(blank=True, help_text='Teams having access (data shared with)', to='user.Team'),
+        ),
+        migrations.AlterField(
+            model_name='intervention',
+            name='users',
+            field=models.ManyToManyField(blank=True, help_text='Users having access (data shared with)', to=settings.AUTH_USER_MODEL),
+        ),
+    ]