Fixed Windows build

Author: JohanMabille

.github/workflows/windows.yml

@@ -28,7 +28,15 @@ jobs:
         cache-environment: true
 
     - name: Configure using CMake
-      run: cmake -Bbuild -DXTENSOR_INSTALL_R_PACKAGES=OFF -G "MinGW Makefiles" -DCMAKE_INSTALL_PREFIX=$CONDA_PREFIX -DDOWNLOAD_GTEST=ON $(Build.SourcesDirectory)
+      run: |
+        cmake -Bbuild \
+          -DXTENSOR_INSTALL_R_PACKAGES=OFF \
+          -DCMAKE_C_COMPILER=$CC \
+          -DCMAKE_CXX_COMPILER=$CXX \
+          -G "MinGW Makefiles" \
+          -DCMAKE_INSTALL_PREFIX=$CONDA_PREFIX \
+          -DDOWNLOAD_GTEST=ON \
+          $(Build.SourcesDirectory)
 
     - name: Install
       working-directory: build