update citation, part of Project-MONAI#8718

Signed-off-by: Yun Liu <yunl@nvidia.com>

Author: KumoLiu

CITATION.cff

@@ -6,8 +6,8 @@ title: "MONAI: Medical Open Network for AI"
 abstract: "AI Toolkit for Healthcare Imaging"
 authors:
   - name: "MONAI Consortium"
-date-released: 2025-09-22
-version: "1.5.1"
+date-released: 2026-01-29
+version: "1.5.2"
 identifiers:
   - description: "This DOI represents all versions of MONAI, and will always resolve to the latest one."
     type: doi