perf(db): release database before exit

internal/db/db.go

@@ -31,3 +31,17 @@ func AutoMigrate(dst ...interface{}) error {
 func GetDb() *gorm.DB {
 	return db
 }
+
+func Close() {
+	log.Info("closing db")
+	sqlDB, err := db.DB()
+	if err != nil {
+		log.Errorf("failed to get db: %s", err.Error())
+		return
+	}
+	err = sqlDB.Close()
+	if err != nil {
+		log.Errorf("failed to close db: %s", err.Error())
+		return
+	}
+}