github-ci: Switch macOS tests over to supported releases.

.github/workflows/autotools-cmake.yml

@@ -46,7 +46,7 @@ jobs:
     strategy:
       matrix:
         include:
-          - os: macos-11
+          - os: macos-14
             configure_args:
             cmake_args:
           - os: ubuntu-20.04

.github/workflows/cppcheck.yml

@@ -43,7 +43,7 @@ permissions:
 jobs:
   checks:
     name: Run Cppcheck
-    runs-on: macos-12
+    runs-on: macos-14
     steps:
     - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b  # v4.1.4
     - name: Install runtime dependencies

.github/workflows/macos.yml

@@ -45,6 +45,7 @@ jobs:
     name: Perform checks
     strategy:
       matrix:
+        os: [macos-12, macos-14]
         include:
           # NOTE: This is a quick port from .travis.yml in reaction to
           #       Homebrew issues at Travis CI.  While we have the matrix
@@ -53,7 +54,7 @@ jobs:
           - MODE: distcheck
           - MODE: qa-sh
             FLAT_ENV: CC=clang CXX=clang++ LD=clang++ QA_SANITIZER=address
-    runs-on: macos-11
+    runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b  # v4.1.4
     - name: Install build dependencies