Had to add `src/strophe-shims.js` as a webpack alias to the shims.js
file in Strophe because the usage of `require` to load Node.js packags
in shims.js is causing problems with Webpack 5.
Set postcss-clean to 1.2.0 to fix the build error `node.getIterator() is
not a function`
Upgrade to latest Webpack
JC Brand