Update macOS runner version for Coverity job (#775)

See: bda7101
6c2de30
See: https://github.blog/changelog/2025-09-19-github-actions-macos-13-runner-image-is-closing-down/

Author: Youw

.github/workflows/checks.yml

@@ -71,7 +71,7 @@ jobs:
 
 
   coverity-macos:
-    runs-on: macos-13
+    runs-on: macos-15-intel
     needs: [coverity-windows]
 
     steps: