[next] Adjust warning in NcPopoverTriggerProvider

[raimund-schluessler]

These lines need to be adjusted for vue 3:

nextcloud-vue/src/components/NcPopover/NcPopoverTriggerProvider.vue

Lines 36 to 44 in 75f177b

	// TODO: Adjust for vue 3. Since vue 3 components can have multiple root elements, this breaks.
	/**
	const rootElement = this.$el
	console.debug(this.$el)
	const innerElement = this.$el.querySelector('[aria-expanded][aria-haspopup]')
	if (!rootElement.getAttribute('aria-expanded') && !innerElement) {
	warn('It looks like you are using a custom button as a <NcPopover> or other popover #trigger. If you are not using <NcButton> as a trigger, you need to bind attrs from the #trigger slot props to your custom button. See <NcPopover> docs for an example.')
	}
	*/

See also the discussion here
#5097 (comment)