ci: migrate intel macos test to macos-15-intel

Author: Zxilly

.github/workflows/built-tests.yml

@@ -65,7 +65,7 @@ jobs:
       checks: write
     strategy:
       matrix:
-        os: [ ubuntu-24.04, ubuntu-24.04-arm, windows-latest, macos-13, macos-14 ]
+        os: [ ubuntu-24.04, ubuntu-24.04-arm, windows-latest, macos-15-intel, macos-14 ]
         test: [ unit, integration-example, integration-real ]
         include:
           - test: unit