CI: Avoid using CMake 4 in the Windows vcpkg runner, for now

For whatever reason, some modern package managers/envs think it's wise to
use 'latest' for about everything.  Even for the most important building
tools, even when said tools release a major new version warning about big
compatibility breakage.

Stay on CMake 3.31 until the ecosystem is fixed for CMake 4.

See actions/runner-images#11926.

Author: dwatteau

.github/workflows/ci.yml

@@ -39,6 +39,10 @@ jobs:
         uses: actions/checkout@v4
       - uses: ilammy/setup-nasm@v1
         if: matrix.useNasm == 'true'
+      - name: Force CMake < 4.0 usage
+        uses: jwlawson/actions-setup-cmake@v2
+        with:
+          cmake-version: '3.31'
       - name: Install vcpkg
         uses: lukka/run-vcpkg@v11
         id: runvcpkg