[github-actions] migrate from macos-12 to macos-14 (#10751)

.github/workflows/build.yml

@@ -408,7 +408,7 @@ jobs:
             CXX: clang++
           - CC: gcc
             CXX: g++
-    runs-on: macos-12
+    runs-on: macos-14
     env:
       CC: ${{ matrix.CC }}
       CXX: ${{ matrix.CXX }}

.github/workflows/posix.yml

@@ -222,7 +222,7 @@ jobs:
 
   pty-macos:
     name: pty-macos OT_DAEMON=${{ matrix.OT_DAEMON }}
-    runs-on: macos-12
+    runs-on: macos-14
     strategy:
       fail-fast: false
       matrix: