Support feature worker declaration from gitlab.teklia.com

Closes #1883 (closed)

• Requires tests

arkindex/process/management/commands/update_system_workers.py

@@ -253,7 +253,7 @@ class Command(BaseCommand):
         for feature_value, feature_config in config["features"].items():
             feature = ArkindexFeature(feature_value)
             self.stdout.write(f" {feature.name} ".center(80, "─"))
-            worker = feature_config.pop("teklia_worker")
+            worker = feature_config.pop("teklia_worker", None)
             if worker is not None:
                 self.update_feature_from_worker(feature, **worker)
             else: