Fix indent after opening tag

[svelterust]

I've noticed there's difference in behaviour between html and svelte mode, and I think it's because this extension is missing following in indents.scm:

(start_tag ">" @end) @indent
(self_closing_tag "/>" @end) @indent

(element
  (start_tag) @start
  (end_tag)? @end) @indent

The issue I'm having is that when my code looks like this (| is cursor):

<h1>|</h1>

And I press enter, it turns into this:

<h1>
    |</h1>

Instead of this:

<h1>
    |
</h1>