chore: bump macOS

The macOS 13 runner will will be retired by 4 December 2025, with jobs
using macOS 13 failing temporarily during scheduled brownout time periods
starting in November.

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

Author: DimitriPapadopoulos

.github/workflows/ci.yml

@@ -73,10 +73,10 @@ jobs:
             runs-on: ubuntu-latest
             cmake-version: "3.20.x"
           - python-version: "3.9"
-            runs-on: macos-13
+            runs-on: macos-15-intel
             cmake-version: "3.18.x"
           - python-version: "3.12"
-            runs-on: macos-13
+            runs-on: macos-15-intel
             cmake-version: "3.29.x"
           - python-version: "3.10"
             runs-on: ubuntu-latest
@@ -162,7 +162,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ["3.8", "3.11"]
-        runs-on: [ubuntu-latest, macos-13, windows-latest]
+        runs-on: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:
       - uses: actions/checkout@v5