Drop support of go1.19 (#1558)

* drop support of Go 1.19

* replace atomicBool by atomic.Bool

* Update Go and MariaDB versions in README.md

Author: shogo82148

README.md

@@ -41,8 +41,8 @@ A MySQL-Driver for Go's [database/sql](https://golang.org/pkg/database/sql/) pac
 
 ## Requirements
 
-* Go 1.19 or higher. We aim to support the 3 latest versions of Go.
-* MySQL (5.7+) and MariaDB (10.3+) are supported.
+* Go 1.20 or higher. We aim to support the 3 latest versions of Go.
+* MySQL (5.7+) and MariaDB (10.5+) are supported.
 * [TiDB](https://github.com/pingcap/tidb) is supported by PingCAP.
   * Do not ask questions about TiDB in our issue tracker or forum.
   * [Document](https://docs.pingcap.com/tidb/v6.1/dev-guide-sample-application-golang)

atomic_bool.go

@@ -17,6 +17,7 @@ import (
 	"net"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"time"
 )
 
@@ -41,7 +42,7 @@ type mysqlConn struct {
 	closech  chan struct{}
 	finished chan<- struct{}
 	canceled atomicError // set non-nil if conn is canceled
-	closed   atomicBool  // set when conn is closed, before closech is closed
+	closed   atomic.Bool // set when conn is closed, before closech is closed
 }
 
 // Handles parameters set in DSN after the connection is established

atomic_bool_go118.go

@@ -1,5 +1,5 @@
 module github.com/go-sql-driver/mysql
 
-go 1.18
+go 1.20
 
 require filippo.io/edwards25519 v1.1.0