fix: Update UCX Ref for Performance (#7218)

Signed-off-by: Adit Ranadive <aranadive@nvidia.com>
Signed-off-by: Dan Gil <dagil@nvidia.com>
Co-authored-by: Adit Ranadive <aranadive@nvidia.com>

Author: dagil-nvidia

container/context.yaml

@@ -23,7 +23,7 @@ dynamo:
   etcd_version: v3.5.21
 
   nixl_ref: 0.10.1
-  nixl_ucx_ref: v1.20.0
+  nixl_ucx_ref: v1.20.x
   nixl_gdrcopy_ref: v2.5.1
   nixl_ucx_efa_ref: 9d2b88a1f67faf9876f267658bd077b379b8bb76
   nixl_libfabric_ref: v2.3.0