Drop support for Go 1.19 and add support for Go 1.21

Author: dhui

README.md

@@ -3,7 +3,7 @@
 [![Coverage Status](https://img.shields.io/coveralls/github/golang-migrate/migrate/master.svg)](https://coveralls.io/github/golang-migrate/migrate?branch=master)
 [![packagecloud.io](https://img.shields.io/badge/deb-packagecloud.io-844fec.svg)](https://packagecloud.io/golang-migrate/migrate?filter=debs)
 [![Docker Pulls](https://img.shields.io/docker/pulls/migrate/migrate.svg)](https://hub.docker.com/r/migrate/migrate/)
-![Supported Go Versions](https://img.shields.io/badge/Go-1.19%2C%201.20-lightgrey.svg)
+![Supported Go Versions](https://img.shields.io/badge/Go-1.20%2C%201.21-lightgrey.svg)
 [![GitHub Release](https://img.shields.io/github/release/golang-migrate/migrate.svg)](https://github.com/golang-migrate/migrate/releases)
 [![Go Report Card](https://goreportcard.com/badge/github.com/golang-migrate/migrate/v4)](https://goreportcard.com/report/github.com/golang-migrate/migrate/v4)