archwiki: Configure permissions as empty arrays

MediaWiki expects arrays and throws errors if a string is found. Using
empty arrays works and the group exists as it should without any
permissions and without errors.

Signed-off-by: Florian Pritz <bluewind@xinu.at>

roles/archwiki/templates/LocalSettings.php.j2

@@ -217,11 +217,11 @@ $wgFooterIcons = ['copyright' => ['copyright' => '']];
 ## specific access levels (see below) as needed.
 ##
 
-$wgGroupPermissions[] = 'maintainer';
-$wgGroupPermissions[] = 'translator';
-$wgGroupPermissions[] = 'archdev';
-$wgGroupPermissions[] = 'archtu';
-$wgGroupPermissions[] = 'archstaff';
+$wgGroupPermissions['maintainer'] = array();
+$wgGroupPermissions['translator'] = array();
+$wgGroupPermissions['archdev'] = array();
+$wgGroupPermissions['archtu'] = array();
+$wgGroupPermissions['archstaff'] = array();
 
 
 ##