Update other webpack packages

[MikeMcC399]

This PR updates

• webpack-cli to the latest version (4.10.0 5.0.0)
• webpack-dev-server (4.11.1)

to resolve deprecation warnings when executing npm run serve (see log in #30):

<i> [webpack-dev-server] [HPM] Proxy created: /api  -> http://localhost:9090
(node:5022) [DEP_WEBPACK_DEV_SERVER_CONSTRUCTOR] DeprecationWarning: Using 'compiler' as the first argument is deprecated. Please use 'options' as the first argument and 'compiler' as the second argument.
(Use `node --trace-deprecation ...` to show where the warning was created)
(node:5022) [DEP_WEBPACK_DEV_SERVER_LISTEN] DeprecationWarning: 'listen' is deprecated. Please use async 'start' or 'startCallback' methods.

[MikeMcC399]

@dreske

This is not urgent, but perhaps you would consider this PR which removes deprecation warnings?