fix(api-bc): lower case cluster id for term comparison

antarest/study/storage/variantstudy/business/utils_binding_constraint.py

@@ -53,7 +53,7 @@ def apply_binding_constraint(
             # Cluster IDs are stored in lower case in the binding constraints file.
             area, cluster_id = link_or_cluster.split(".")
             thermal_ids = {thermal.id.lower() for thermal in study_data.config.areas[area].thermals}
-            if area not in study_data.config.areas or cluster_id not in thermal_ids:
+            if area not in study_data.config.areas or cluster_id.lower() not in thermal_ids:
                 return CommandOutput(
                     status=False,
                     message=f"Cluster '{link_or_cluster}' does not exist in binding constraint '{bd_id}'",