Fix release workflow: use macos-15 for x86_64 build

macos-13 runners are no longer available on GitHub Actions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sovanesyan

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
         include:
           - os: macos-14
             target: aarch64-apple-darwin
-          - os: macos-13
+          - os: macos-15
             target: x86_64-apple-darwin
     runs-on: ${{ matrix.os }}
     steps: