CI: Replace macos-12 with macos-15 due to deprecation

macos-12 runner image will be fully retired by the December 3rd, 2024.
https://github.blog/changelog/2024-08-19-notice-of-upcoming-deprecations-and-breaking-changes-in-github-actions-runners/

Author: Biswa96

.github/workflows/build.yml

@@ -168,7 +168,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-12, macos-13, macos-14]
+        os: [macos-13, macos-14, macos-15]
     runs-on: ${{ matrix.os }}
     needs: [upload-src]
     steps: