ci: macos-13 -> macos-15-intel

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

Author: elopez

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     needs: [lint, test]
     strategy:
       matrix:
-        environment: [ubuntu-latest, macos-13, macos-14, windows-latest]
+        environment: [ubuntu-latest, macos-15-intel, macos-14, windows-latest]
     permissions:
       contents: read
       id-token: write
@@ -157,7 +157,7 @@ jobs:
   test:
     strategy:
       matrix:
-        environment: [ubuntu-latest, macos-13, macos-14, windows-latest]
+        environment: [ubuntu-latest, macos-15-intel, macos-14, windows-latest]
 
     runs-on: ${{ matrix.environment }}
     timeout-minutes: 20