CI: update macos version (gh deprecation)

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

macos-13 is being deprecated, instead we add the new macos-15-intel and macos-26.

Signed-off-by: Peter M <[email protected]>

Author: petermm

.github/workflows/build-and-test-macos.yaml

@@ -38,7 +38,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: ["macos-13", "macos-14"]
+        os: ["macos-14", "macos-15", "macos-15-intel", "macos-26"]
         otp: ["24", "25", "26"]
 
     steps: