upgrade go-sql-driver/mysql to fix invalid connection error (#5748)

should fix #5736

vendor/github.com/go-sql-driver/mysql/utils_go18.go

@@ -1,50 +0,0 @@
-// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
-//
-// Copyright 2017 The Go-MySQL-Driver Authors. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// +build go1.8
-
-package mysql
-
-import (
-	"crypto/tls"
-	"database/sql"
-	"database/sql/driver"
-	"errors"
-	"fmt"
-)
-
-func cloneTLSConfig(c *tls.Config) *tls.Config {
-	return c.Clone()
-}
-
-func namedValueToValue(named []driver.NamedValue) ([]driver.Value, error) {
-	dargs := make([]driver.Value, len(named))
-	for n, param := range named {
-		if len(param.Name) > 0 {
-			// TODO: support the use of Named Parameters #561
-			return nil, errors.New("mysql: driver does not support the use of Named Parameters")
-		}
-		dargs[n] = param.Value
-	}
-	return dargs, nil
-}
-
-func mapIsolationLevel(level driver.IsolationLevel) (string, error) {
-	switch sql.IsolationLevel(level) {
-	case sql.LevelRepeatableRead:
-		return "REPEATABLE READ", nil
-	case sql.LevelReadCommitted:
-		return "READ COMMITTED", nil
-	case sql.LevelReadUncommitted:
-		return "READ UNCOMMITTED", nil
-	case sql.LevelSerializable:
-		return "SERIALIZABLE", nil
-	default:
-		return "", fmt.Errorf("mysql: unsupported isolation level: %v", level)
-	}
-}