Adds a deploy workflow

[orta]

This sets up GitHub to deploy packages when they change on a nightly basis. Sharing the infra with https://github.com/sveltejs/language-tools/

So for example, because I merged #51 today - then that package is the only one which would be deployed tomorrow morning

I don't have access to deploy the module, so I'm afraid adding the NPM access token in the security section - my recommendation is to make a shiki-only bot account to deploy so that your credentials don't go in there

[octref]

I'm thinking if we should publish nightly build behind a tag. We can make it easy to update vls dependencies in Vetur, but IMO there should be two modes:

1. For people who want the latest changes/bugfixes
2. For people who need a stable enviroment to get things done

[orta]

I do that in svelte too, but both of those reps get a lot of PRs - this repo generally doesn't

[octref]

I'll set it up after next release. Doing a lot of changes.

[octref]

Did you create https://www.npmjs.com/org/shiki-bot?

[octref]

Feeling this would have unintended consequences — for example, I might have half-done changes on master that I want to polish before publishing.
Also the Changelog.md need to be updated manually still.
So opting not to use it. I'll add you on NPM for the packages.

[orta]

Cool, totally reasonable!