fix: Fix registration status verification logic

Updates registration completion check to validate
that the status is 'STATUS_STARTED' instead of
'STATUS_REQUESTED'. This corrects the flow for
properly handling completed registrations.

This change ensures users with started registrations
are processed correctly.

src/synapse_registration/registration/views.py

@@ -184,7 +184,7 @@ class CompleteRegistrationView(FormView):
             UserRegistration, id=self.request.session.get("registration")
         )
         if (
-            self.registration.status != UserRegistration.STATUS_REQUESTED
+            self.registration.status != UserRegistration.STATUS_STARTED
             or not self.registration.email_verified
         ):
             return render(request, "registration/registration_forbidden.html", status=403)