Update release branch to 26.02 for upcoming release nightly build (#751)

## Issue

Authors:
  - Ramakrishnap (https://github.com/rgsl888prabhu)

Approvers:
  - Trevor McKay (https://github.com/tmckayus)

URL: #751

Author: rgsl888prabhu

.github/workflows/nightly.yaml

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION. All rights reserved.
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026, NVIDIA CORPORATION. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
 name: Trigger Nightly cuOpt Pipeline
@@ -17,7 +17,7 @@ jobs:
       matrix:
         cuopt_branch:
           - "main"
-          - "release/25.12"
+          - "release/26.02"
     steps:
       - uses: actions/checkout@v4
       - name: Trigger Pipeline