Fix detection of build 503

removeAll removes all instances of an item in the right list from the
left list, but we only want to remove a single instance.

Signed-off-by: Graham <gpe@openrs2.org>

archive/src/main/kotlin/org/openrs2/archive/client/ClientImporter.kt

@@ -614,7 +614,9 @@ public class ClientImporter @Inject constructor(
                 }
             }
 
-            candidates -= NEW_ENGINE_RESOLUTIONS
+            for (build in NEW_ENGINE_RESOLUTIONS) {
+                candidates -= build
+            }
 
             val version = candidates.singleOrNull()
             if (version != null) {