[core] Update Entities (#6885)

esphome/components/update/update_entity.cpp

@@ -0,0 +1,12 @@
+#include "update_entity.h"
+
+namespace esphome {
+namespace update {
+
+void UpdateEntity::publish_state() {
+  this->has_state_ = true;
+  this->state_callback_.call();
+}
+
+}  // namespace update
+}  // namespace esphome