修复：并发事务的线程安全问题

core/iTransaction.go

@@ -6,11 +6,11 @@ import "database/sql"
 type ITransaction interface {
 	// Begin 开始
 	// isolationLevels：事务等级
-	Begin(isolationLevels ...sql.IsolationLevel)
+	Begin(isolationLevels ...sql.IsolationLevel) error
 	// Commit 提交
 	Commit()
 	// Rollback 回滚
 	Rollback()
 	// Transaction 使用事务
-	Transaction(executeFn func())
+	Transaction(executeFn func(), isolationLevels ...sql.IsolationLevel)
 }