Use testing farm production instance in packit stage instance (#588)

While the testing farm staging instance is not available

Author: majamassarini

secrets/packit/stg/packit-service.yaml.j2

@@ -8,7 +8,9 @@ validate_webhooks: true
 
 {{ vault.packit_service | to_nice_yaml }}
 
-testing_farm_api_url: https://api.staging.testing-farm.io/v0.1/
+# temporarily unavailable, use production in the meanwhile
+# testing_farm_api_url: https://api.staging.testing-farm.io/v0.1/
+testing_farm_api_url: https://api.testing-farm.io/v0.1/
 enabled_projects_for_internal_tf:
   - github.com/packit/hello-world
   - github.com/packit/specfile