COMP: Upgrade bit-rotted macOS runner pins to macos-14 house canonical

The `build-test-cxx` job (and its paired `matrix.os == 'macos-*'`
XCode-select conditional) and the `build-test-notebooks` job in
.github/workflows/build-test-publish.yml pinned `macos-13`, which is
now a deprecated GitHub Actions runner image.  The
`build-test-python-superbuild` job already targets `macos-15`, so it
is intentionally left alone (the "do not downgrade" rule wins over
strict convergence on the house canonical).

Update the two `macos-13` entries -- matrix lines and include:
blocks, plus the matching `matrix.os == 'macos-13'` conditional that
selects the pinned Xcode 14.3.1 -- to `macos-14`.  This matches the
canonical runner triple `[ubuntu-24.04, windows-2022, macos-14]`
used by the other ITK remote modules (VkFFTBackend,
WebAssemblyInterface, ...) and keeps the Xcode pinning step wired up
(Xcode 14.3.1 is still shipped in the `macos-14` image).  The
`build-test-documentation` job is ubuntu-only and is not touched.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hjmjohnson

.github/workflows/build-test-publish.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       max-parallel: 3
       matrix:
-        os: [ubuntu-24.04, windows-2022, macos-13]
+        os: [ubuntu-24.04, windows-2022, macos-14]
         include:
           - os: ubuntu-24.04
             c-compiler: "gcc"
@@ -21,7 +21,7 @@ jobs:
             c-compiler: "cl.exe"
             cxx-compiler: "cl.exe"
             cmake-build-type: "Release"
-          - os: macos-13
+          - os: macos-14
             c-compiler: "clang"
             cxx-compiler: "clang++"
             cmake-build-type: "MinSizeRel"
@@ -45,7 +45,7 @@ jobs:
         uses: lukka/get-cmake@v3.24.2
 
       - name: Specific XCode version
-        if: matrix.os == 'macos-13'
+        if: matrix.os == 'macos-14'
         run: |
           sudo xcode-select -s "/Applications/Xcode_14.3.1.app"
 
@@ -234,7 +234,7 @@ jobs:
     strategy:
       max-parallel: 3
       matrix:
-        os: [ubuntu-24.04, windows-2022, macos-13]
+        os: [ubuntu-24.04, windows-2022, macos-14]
 
     steps:
       - uses: actions/checkout@v4