See if we can get msvc builds working.

Author: cfis

.github/workflows/testing.yml

@@ -43,17 +43,20 @@ jobs:
         include:
           - os: ubuntu-latest
             preset: linux-debug
+            ruby: '4.0'
           - os: macos-latest
             preset: macos-debug
+            ruby: '4.0'
           - os: windows-2025
             preset: msvc-debug
+            ruby: mswin
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v6
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: '4.0'
+        ruby-version: ${{ matrix.ruby }}
     - name: Install libffi (Ubuntu)
       if: runner.os == 'Linux'
       run: sudo apt-get install -y libffi-dev
@@ -63,6 +66,9 @@ jobs:
     - name: Install libffi (Windows)
       if: runner.os == 'Windows'
       run: vcpkg install libffi:x64-windows
+    - name: Set up MSVC
+      if: runner.os == 'Windows'
+      uses: ilammy/msvc-dev-cmd@v1
     - name: Configure
       run: cmake --preset ${{ matrix.preset }} -DCMAKE_CXX_STANDARD=${{ matrix.cpp_standard }}
     - name: Build