homeassistant: expose sleep_mode to google

modules/services/homeassistant.nix

@@ -81,6 +81,11 @@ in
             report_state = true;
             expose_by_default = true;
             exposed_domains = [ "light" ];
+            entity_config = {
+              input_boolean.sleep_mode = {
+                expose = true;
+              };
+            };
           };
           homekit = [{
             filter = {