Merge #1624: ci: Update macOS image

096e3e2 ci: Update macOS image (Hennadii Stepanov)

Pull request description:

  The macOS 12 GHA image has been deprecated since 2024-10-07. See: actions/runner-images#10721.

  Draft for now as `./libtool --mode=execute valgrind --error-exitcode=42 ./ctime_tests` fails.

ACKs for top commit:
  real-or-random:
    ACK 096e3e2

Tree-SHA512: 715e7d2638bb7161c756d3856ee7eb6826f2300ab215deb888f040881c6b8cddc311c206f90dd942844ee2e56247e8ca99078a229e80ef086c2a4fdd8937af9d

.github/workflows/ci.yml

@@ -612,9 +612,9 @@ jobs:
         if: ${{ always() }}
 
   x86_64-macos-native:
-    name: "x86_64: macOS Monterey, Valgrind"
+    name: "x86_64: macOS Ventura, Valgrind"
     # See: https://github.com/actions/runner-images#available-images.
-    runs-on: macos-12
+    runs-on: macos-13
 
     env:
       CC: 'clang'