fix: update svelte to 3.37.0

[nolanlawson]

Incidentally this fixes #149.

TODO:

• add tests that this doesn't break older versions of Svelte before the mount/disconnected fixes
• figure out why svelte 3.38.0 causes one of the tests to break

[nolanlawson]

Hm, this causes a memory leak because disconnecting the custom element no longer destroys the Svelte component, which means that the ResizeObserver action's destroy() is never called. Interesting puzzle.

[nolanlawson]

Realized tests for old Svelte probably aren't possible. I think since I'm not going to make Svelte a peerDependency I should just add a note to the readme that if you're using import Picker from 'emoji-picker-element/svelte' then you should make sure it's a roughly compatible Svelte version.

[nolanlawson]

The failed test in Svelte 3.38.0 is due to changing the order of items in a keyed each block, so it looks like the same issue as sveltejs/svelte#6444

Svelte 3.38.0 also seems to increase the code side a fair amount, apparently due to hydration code being added, even though the component is not hydratable. Seems due to: sveltejs/svelte@10e3e3d

[nolanlawson]

I filed a bug about the size increase: sveltejs/svelte#6462

Due to that and the keyed each bug, we'll probably want to hold off on updating to Svelte 3.38.0+ for now.