Steps to reproduce

1. Use Node 16 (and therefore npm 8 where peerDependencies are always installed)
2. Create a package.json with both higlass and a package requiring webpack 5
3. Due to unminified-webpack-plugin: ^2.0.0, it will always install webpack 4 on the root level of node_modules

Observed behavior

• With node_modules/webpack being of version 4, it breaks some scripts which rely on it being on version 5.

Expected behavior

• It should not at all install unminified-webpack-plugin as dependency, but probably devDependency?

Here, unminified-webpack-plugin is tagged to version ^2.0.0. One could either upgrade to ^3.0.0 (which is webpack 5 only), or move it to devDependencies. Is there a reason why it is included in dependencies instead?