Clean up

[AlexEne]

I'm opening this to provide some visibility on what I'm working on.
The repo is a bit stale and requires some care before we can add some new features (e.g. I'm excited about #581, I have some prototype, it's easy to use and has super nice results).

But before we can have nice shiny things some cleanup must be done:

• Enable github actions: #580
• Run the tests on windows (part of task above). Now I need to work in WSL on my machine and it's a bit of a pain as the wrong \r\n in a .sh file confuses up test script :)
• Update dependencies: This will be a bit of a pain as dependabot is trying, but I've manually checked some of them and they don't compile. Not having a working CI isn't ideal either.
• Add lib.rs clippy deny lints with deny so we keep this as idiomatic as possible.
• Remove failure dependency. This is probably from a time when main couldn't return a Result.

I'll add more stuff if I find it, but so far this seems like a good plan.

[AlexEne]

Removing the failure dependency seems to be more pressing as this is now open: https://github.com/rustwasm/twiggy/security/dependabot/1

I don't think we're getting any benefit from using it vs this_error / anyhow, so I'll just move to depend on those.