Update registry.h code formatting

include/spdlog/details/registry.h

@@ -68,7 +68,10 @@ public:
         periodic_flusher_ = details::make_unique<periodic_worker>(clbk, interval);
     }
 
-    std::unique_ptr<periodic_worker> &get_flusher() { std::lock_guard<std::mutex> lock(flusher_mutex_); return periodic_flusher_; }
+    std::unique_ptr<periodic_worker> &get_flusher() {
+        std::lock_guard<std::mutex> lock(flusher_mutex_); 
+        return periodic_flusher_; 
+    }
 
     void set_error_handler(err_handler handler);