style: use short block notation in the module router spec

Ameba runs in CI but not in ./test, so this slipped through when the
router specs landed on master.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: stakach

spec/router/module_router_spec.cr

@@ -54,7 +54,7 @@ module PlaceOS::Source
         Router::Module.new(mappings).handle_delete(mod)
 
         mappings.read(&.drivers).should eq({"mod-stays" => "driver-sns"})
-        mappings.read { |current| current.system_modules.has_key?("mod-gone") }.should be_false
+        mappings.read(&.system_modules.has_key?("mod-gone")).should be_false
       end
     end