go the fetch route for windows

.gitlab-ci.yml

@@ -611,8 +611,6 @@ macOS12_Xcode13:
   - choco install ccache -y
   - choco install vswhere -y
   - choco install python -y
-  - vcpkg install cxxopts
-  - vcpkg integrate install
   - refreshenv
   - |
     function Make-SafeFileName {

CI/before_script.msvc.sh

@@ -1036,7 +1036,7 @@ add_cmake_opts -DOPENMW_MP_BUILD=on
 add_cmake_opts -DCMAKE_INSTALL_PREFIX="${INSTALL_PREFIX}"
 add_cmake_opts -DOPENMW_USE_SYSTEM_SQLITE3=OFF
 add_cmake_opts -DOPENMW_USE_SYSTEM_YAML_CPP=OFF
-add_cmake_opts -DCMAKE_TOOLCHAIN_FILE="C:/vcpkg/scripts/buildsystems/vcpkg.cmake"  # add vcpkg toolchain
+add_cmake_opts -DOPENMW_USE_SYSTEM_CXXOPTS=OFF
 if [ ! -z $CI ]; then
 	case $STEP in
 		components )