Svelte 5 bug preventing upgrade

[ciscoheat]

The following issue prevents Superforms v2 to be fully compatible with Svelte 5: sveltejs/svelte#9947

Everything works but bind:group due to this.

[ciscoheat]

sveltejs/svelte#9947 has just been closed, waiting for the next release!

[ciscoheat]

Unfortunately it wasn't fully fixed with that, have to wait for this now: sveltejs/svelte#10379

[ciscoheat]

sveltejs/svelte#10379 is fixed now so it's pretty much working!
This one makes a test fail, but it's not directly related to Superforms: sveltejs/svelte#10426

[ciscoheat]

The test didn't initialize the props properly in the parent, so there's a workaround. Closing this now, we got Svelte 5 compatibility for v2!