chore: use macos-15-intel runner for MacOS x86_64 builds

Author: giacomocusinato

.github/workflows/build.yml

@@ -103,7 +103,7 @@ env:
           name: Linux_X86-64_app_image
     - config:
         name: macOS x86
-        runs-on: macos-13
+        runs-on: macos-15-intel
         container: |
           null
         # APPLE_SIGNING_CERTIFICATE_P12 secret was produced by following the procedure from: