Update monolithic-windows.sh

Author: makslevental

.ci/monolithic-windows.sh

@@ -54,6 +54,8 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
       -DLLVM_INCLUDE_UTILS=ON \
       -DLLVM_INSTALL_UTILS=ON
 
+ninja -C "${BUILD_DIR}" -k 0 install
+
 start-group "ninja"
 
 # Targets are not escaped as they are passed as separate arguments.