Remove divider in app content list (Mail, Contacts, …)

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

core/css/apps.scss

@@ -1122,7 +1122,6 @@ $outter-margin: ($popoveritem-height - $popovericon-size) / 2;
 	.app-content-list-item {
 		position: relative;
 		height: 68px;
-		border-top: 1px solid var(--color-border);
 		cursor: pointer;
 		padding: 10px 7px;
 		display: flex;