fix(backend): Fix webhook ingress URL generation (#9209)

The enum's string *representation* was being inserted in the URL instead
of its string *value*.

Before:
`/api/integrations/ProviderName.GITHUB/webhooks/686db48c-e70d-4340-acf9-ccd0338fddc4/ingress`

After:
`/api/integrations/github/webhooks/686db48c-e70d-4340-acf9-ccd0338fddc4/ingress`

---------

Co-authored-by: Nicholas Tindle <nicholas.tindle@agpt.co>

autogpt_platform/backend/backend/data/integrations.py

@@ -35,7 +35,7 @@ class Webhook(BaseDbModel):
     @computed_field
     @property
     def url(self) -> str:
-        return webhook_ingress_url(self.provider.value, self.id)
+        return webhook_ingress_url(self.provider, self.id)
 
     @staticmethod
     def from_db(webhook: IntegrationWebhook):

autogpt_platform/backend/backend/integrations/webhooks/utils.py

@@ -1,10 +1,11 @@
+from backend.integrations.providers import ProviderName
 from backend.util.settings import Config
 
 app_config = Config()
 
 
 # TODO: add test to assert this matches the actual API route
-def webhook_ingress_url(provider_name: str, webhook_id: str) -> str:
+def webhook_ingress_url(provider_name: ProviderName, webhook_id: str) -> str:
     return (
         f"{app_config.platform_base_url}/api/integrations/{provider_name}"
         f"/webhooks/{webhook_id}/ingress"