archwiki: Update deprecated $wgLogo to $wgLogos

Otherwise, we would get an error:
	The key `1x` is required for wgLogos or wgLogo must be defined

See the release notes for details:
https://www.mediawiki.org/wiki/Special:MyLanguage/Release_notes/1.35#Configuration_changes_for_system_administrators_in_1.35

roles/archwiki/templates/LocalSettings.php.j2

@@ -54,7 +54,7 @@ $wgStylePath        = "$wgScriptPath/skins";
 
 ## The relative URL path to the logo.
 ## Set to an empty string so no logo is loaded by default.
-$wgLogo             = "";
+$wgLogos = ["1x" => ""];
 
 ## For attaching licensing metadata to pages, and displaying an
 ## appropriate copyright notice / icon. GNU Free Documentation