Enhancement: use charfield for webhook url, custom validation (#9128)

---------

Co-authored-by: Trenton H <797416+stumpylog@users.noreply.github.com>

src/documents/migrations/1063_alter_workflowactionwebhook_url.py

@@ -0,0 +1,22 @@
+# Generated by Django 5.1.6 on 2025-02-16 16:31
+
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("documents", "1062_alter_savedviewfilterrule_rule_type"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="workflowactionwebhook",
+            name="url",
+            field=models.CharField(
+                help_text="The destination URL for the notification.",
+                max_length=256,
+                verbose_name="webhook url",
+            ),
+        ),
+    ]