fix(CI): set CMAKE_POLICY_VERSION_MINIMUM environment variable (#4692)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Chores**
- Updated internal testing configuration by adding a new parameter to
enforce a minimum version requirement for build policies.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

Author: njzjz

.github/workflows/test_python.yml

@@ -43,6 +43,8 @@ jobs:
         HOROVOD_WITH_TENSORFLOW: 1
         HOROVOD_WITHOUT_PYTORCH: 1
         HOROVOD_WITH_MPI: 1
+        # https://cmake.org/cmake/help/latest/variable/CMAKE_POLICY_VERSION_MINIMUM.html
+        CMAKE_POLICY_VERSION_MINIMUM: 3.5
     - run: dp --version
     - name: Get durations from cache
       uses: actions/cache@v4