Upgrade most of gems

[JuanitoFatas]

This PR:

• Use Rails 6 and other gems
• Lock rouge because syntax highlight css classes changed (we should upgrade this separately)
• Simplify Page#render

[yob]

Upgrade all of the things!

My personal preference is to upgrade gems in smaller batches over multiple PRs, so testing each PR is easier and any surprises are easier to track down.

This is a pretty simple app though, so maybe we can get away with all-at-once?

[JuanitoFatas]

My personal preference is to upgrade gems in smaller batches over multiple PRs

We can turn on dependantbot and configure it in a less noisy way.

This is a pretty simple app though, so maybe we can get away with all-at-once?

The tests passed and clicking through the reviews app everything looks okay.

[plaindocs]

I'm 👍 on dependabot ongoing.

I've clicked around the review app and looks fine.

Thanks for diving in @JuanitoFatas .

[JuanitoFatas]

@matthewd What do you think about the change here? 🙇‍♂️

[matthewd]

The first line is mutating a global value, but this method gets called multiple times.

Sounds to me like the append_view_path should be in PagesController, then this would be:

def render(partial)
  PagesController.render(partial: partial)
end

[JuanitoFatas]

Thanks! Fixed in 4488f93.