feat: slack themes

[codepunkt]

Fixes #75

[octref]

Sorry, I just realized that I didn't finish the script. Can you rebase off master and run yarn:update-themes again?
Also, why only choose two of the themes?

[codepunkt]

Wasn't sure how many you'd want. Those are the two that i'm using. I can add all of them for a better/full experience. Should i?

[octref]

Can you please only add ochin? I think all the themes have same syntax highlighting, just different workspace colors.
Aubergine dark is the only one with different syntax highlighting, but it doesn't look that good to me.

[codepunkt]

That doesn't fit my usecase. I need two of them, and a good solution to switch between them for light/dark mode.

If this is not mergeable here, i'll use my fork.

[octref]

That doesn't fit my usecase. I need two of them, and a good solution to switch between them for light/dark mode.

OK, that makes sense.

There's a script to update theme source https://github.com/shikijs/shiki/blob/master/scripts/pullGHThemes.sh#L6

I rebased off origin/master and made the necessary changes.

[codepunkt]

Awesome, thanks @octref! 👍
Whenever you decide you'd also want to have the other Slack themes, i can do that.