Remove webpacker as a dependency

[rossta]

Fixes #145

This PR removes webpacker as a Ruby dependency to prevent conflicts in apps that are moving from Webpacker to Shakapacker.

Changes:

Please ensure that:

• Changelog is updated if not a minor patch
• Ruby linting is ok: rubocop is all green
• Javascript linting is ok: cd javascript/webpacker_react-npm-module/ && yarn lint is all green
• Tests are all green

[rossta]

I'm now seeing some work to rewrite the project in a non-Webpacker form https://github.com/renchap/webpacker-react/compare/react-components-rails. Let me know if you could use help moving the react-component-rails work forward.

I could see some value in releasing this change as an intermediate step as I currently need to work off my own fork.

[rossta]

I've also done some work to upgrade development dependencies and the CircleCI config to get tests passing.

[renchap]

Hi @rossta and thanks for your PR.

As you saw in #139, I plan to rename this gem to react-components-rails soon after a full rewrite. It no longers depend on Webpacker (or any Rails JS integration) and only contains light helpers to use React components in rails.

A beta version is release (and I have been using it in my projects) and I would encourage you to try it and tell me if it works for you. I am a bit overwhelmed with other work lately, but I still plan to make the big move in the coming weeks and deprecate webpacker-rails (with a message on gem install saying so on the linked PR).

I do not really want to make any change to the current webpacker-rails gem, so I will not merge your PR, as I think react-components-rails will give you what you want with far less code and dependencies.