Fix deprecated webpack config

[MilesMcBain]

output: {
path: resolve(__dirname, "inst/htmlwidgets"),
filename: "[name].js",
library: {
name: "rdeckControls",
type: "umd",
},
}

[MilesMcBain]

remove: https://github.com/qfes/rdeck.controls/blob/master/webpack.config.js#L21