optimize-css-assets-webpack-plugin无法实现压缩css，打包过程中会出现
[DEP_WEBPACK_COMPILATION_OPTIMIZE_CHUNK_ASSETS] DeprecationWarning: optimizeChunkAssets is deprecated (use Compilation.hooks.processAssets instead and use one of Compilation.PROCESS_ASSETS_STAGE_* as stage option)
这是因为optimize-css-assets-webpack-plugin 在webpack5中已不在友好支持
解决办法 使用 css-minimizer-webpack-plugin 为webpack5支持版
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin(),
],
