Fix colors of icons in the modal

Signed-off-by: Joas Schilling <coding@schilljs.com>

css/icons.scss

@@ -9,6 +9,7 @@
 @include icon-black-white('lobby', 'spreed', 1);
 
 .app-Talk,
+.talk-modal,
 #call-container {
 	// We always want to use the white icons, this is why we don't use var(--color-white) here.
 	.icon-public {

src/components/LeftSidebar/NewGroupConversation/NewGroupConversation.vue

@@ -35,7 +35,7 @@
 			size="full"
 			@close="closeModal">
 			<div
-				class="new-group-conversation">
+				class="new-group-conversation talk-modal">
 				<div
 					class="new-group-conversation__content">
 					<template