CI: Workaround VcPkg installation issue

Set an env variable to allow installing e.g. FFTW with CMake 4.x
See microsoft/vcpkg#44746

Author: Flamefire

.github/workflows/build.yml

@@ -54,6 +54,7 @@ jobs:
 
     - name: Install Windows dependencies
       if: startsWith(matrix.os,'windows')
+      env: {CMAKE_POLICY_VERSION_MINIMUM: 3.5}  # See https://github.com/microsoft/vcpkg/issues/44746
       run: |
         vcpkg install libsndfile:x64-windows opus:x64-windows fftw3:x64-windows