fix(terraform): turn on manual integration

we don't want Azure continuous deployment / webhooks

terraform/app_service.tf

@@ -102,9 +102,10 @@ resource "azurerm_linux_web_app" "main" {
 }
 
 resource "azurerm_app_service_source_control" "main" {
-  app_id   = azurerm_linux_web_app.main.id
-  repo_url = "https://github.com/cal-itp/benefits"
-  branch   = local.env_name
+  app_id                 = azurerm_linux_web_app.main.id
+  repo_url               = "https://github.com/cal-itp/benefits"
+  branch                 = local.env_name
+  use_manual_integration = true
 }
 
 resource "azurerm_app_service_custom_hostname_binding" "main" {