fix: the webhook url to be text (#13157)

## Description
Change the url type from string to text, to support more than 255
characters

Fixes # (issue)
https://app.chatwoot.com/app/accounts/1/conversations/65240

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

db/migrate/20251229081141_change_webhook_url_to_text.rb

@@ -0,0 +1,9 @@
+class ChangeWebhookUrlToText < ActiveRecord::Migration[7.1]
+  def up
+    change_column :webhooks, :url, :text
+  end
+
+  def down
+    change_column :webhooks, :url, :string
+  end
+end