CI: Replace the macos-13 images with the macos-15-intel images (#5002)

per
https://github.blog/changelog/2025-09-19-github-actions-macos-13-runner-image-is-closing-down/

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

## Summary by CodeRabbit

* **Chores**
* Updated macOS build matrix in CI to use macOS 15 Intel runners for
x86_64 wheel builds, keeping Python versions and other matrix settings
unchanged.
* No user-facing changes; application behavior remains the same. This
update only affects build infrastructure, improving reliability and
maintaining platform coverage.

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

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

Author: njzjz

.github/workflows/build_wheel.yml

@@ -37,7 +37,7 @@ jobs:
             cuda_version: 11.8
             dp_pkg_name: deepmd-kit-cu11
           # macos-x86-64
-          - os: macos-13
+          - os: macos-15-intel
             python: 311
             platform_id: macosx_x86_64
             dp_variant: cpu